Application guidelines - Danfossfiles.danfoss.com/TechnicalInfo/Dila/17/FRCC.PC.031.A2.22-VRT... · Danfoss Inverter Scrolls R410A Tailored for Trane Residential use only Application

Danfoss Inverter Scrolls R410ATailored for Trane Residential use only

Application guidelines

http://danfoss.us.com/


3FRCC.PC.031.A2.22

Content

Introduction ..................................................... 4Scroll compressor components......................................4Compressor size ...................................................................4Performance ..........................................................................4

Compressor model designation ..................... 5Nomenclature .......................................................................5Label .........................................................................................5Serial number........................................................................5

Technical specifications .................................. 6Compressor specifications ...............................................6Performance data ...............................................................6Inverter drive specifications ............................................6Bearings lubrication ...........................................................6

Dimensions ...................................................... 7VRJ-T 028 - 035 - 044 ...........................................................7

Electrical data, connections and wiring ......... 8Supply Voltage .....................................................................8Compressor electrical specifications ............................8LRA (Locked Rotor Amp) ...................................................8MCC (Maximum Continuous Current) ..........................8Winding resistance..............................................................8Wiring connections ............................................................8Terminal cover mounting .................................................9Terminal cover removal .....................................................9IP rating ...................................................................................9Internal motor protection ................................................9Phase sequence and reverse rotation protection ....9

Approvals and certificates ............................ 10Approval and certificates ................................................10Pressure equipment directive 97/23/EC ...................10Internal free volume .........................................................10Refrigerant and lubricants..............................................11

Operating conditions .................................... 11Motor supply .......................................................................11Compressor ambient temperature .............................11Application envelope .......................................................12High and low pressure protection...............................13Crankcase heating .............................................................13Oil return management ..................................................13On/off cycling (cycle rate limit) ....................................14Start-up sequence .............................................................14

System design recommendations ............... 15General ..................................................................................15Essential piping design considerations .....................15Refrigerant charge limit .................................................16Reversible heat pump systems .....................................16Minimum sump superheat ............................................16Preventing liquid flood back ........................................16Loss of charge protection ...............................................17Oil level checking and top-up .......................................17

Sound and vibration management .............. 18Starting sound level..........................................................18Running sound level ........................................................18LPR sound level ..................................................................18Stopping sound level .......................................................18Sound generation in a refrigeration system and air conditioning system ..........................................18Electro Magnetic Interference (EMI) ...........................19

Installation ..................................................... 20System cleanliness ............................................................20Compressor handling and storage..............................20Compressor mounting ....................................................20Compressor holding charge ..........................................20Tube brazing procedure ..................................................20Brazing material .................................................................20Compressor connection ..................................................21Vacuum evacuation and moisture removal .............21Liquid line filter driers ......................................................22Refrigerant charging ........................................................22Insulation resistance and dielectric strength ..........22Compressor replacement after motor burn out.....22

Ordering information and packaging ......... 23Packaging ............................................................................23Ordering code numbers ..................................................23Accessory ..............................................................................23


4 FRCC.PC.031.A2.22

Introduction

Scroll compressor components

Compressor size

Performance

Danfoss Inverter Scroll compressors for resi-dential applications developed by Danfoss are available in four nominal system sizes (2, 3, 4 and 5 TR), based on three compressor models.

This Selection & Application Guideline focuses on the Inverter scroll compressor.

The Danfoss Inverter Scroll compressor includes dome (upper shell) temperature sensor for ther-mal protections.

The motor stator is rigidly attached to the shell. The rotor is shrink-fit onto the eccentric shaft. The shaft is supported by two bearings, one in the crankcase and the second below the motor.

EMI (Electro-Magnetic Interference) bracket provided allows for grounding termination of shielded wire-harness, which reduces EMI emissions between drive and compressor. Dome bracket mounting is a housing provided for the dome sensor which is located on the upper shell of the compressor.

Inverter technology offers more flexibility in com-pressor selection than fixed speed compressors. Selection of the right Inverter compressor size can be done by different methods:

• Maximum cooling capacity: select a compres-sor size that achieves the peak load system cooling capacity demand at its maximum speed.

• Nominal cooling capacity: select a compressor size that achieves the nominal system cool-ing capacity at a rotational speed of 3000-6000 rpm (50-100Hz).

• Best Seasonal Efficiency Ratio: select a com-pressor size that achieves the minimum system cooling demand at its minimum speed. Ensure that the compressor is able to cover the peak load system cooling capacity. This selection makes the compressor run for maximum time at part load where the system efficiency is highest.

Danfoss Inverter Scroll compressors are manu-factured using the most advanced machining, assembly, and process control techniques. In de-sign of both the compressor and the factory, very high standards of reliability and process control were first priority. The result is a highly efficient product with the highest reliability obtainable, and a low sound level.

The Danfoss Inverter Scroll compressor referenced in this guide is a fully compliant scroll and actually improves with run time in its early commissioning.

A twenty four hour run-in is recommended to meet performance expectations.


5FRCC.PC.031.A2.22

Compressor model designation

Label

Serial number

Nomenclature

K 123450903

Production year

Production week Incremental number

Application, Family& refrigerant V: Variable speed R: Residential J: R410A, PVE lubricant

Swept VolumeDisplacement in cc/rev

Model VariationT: Design optimised for 7.2/54.4°C

Other features6: No other features

Equipment versionP: Brased connections, spade terminals

Motor protectionN: No internal motor protection (protection by drive)

VoltageK: 420V DCL IPM

T

Model Variation

028

Swept Volume

VRJ

Application, Family

& Refrigerant

K

Voltage

N

Motor Protection

P

EquipmentVersion

6

Other Features


6 FRCC.PC.031.A2.22

Technical specifications

Performance data

Inverter drive specifications

Bearings lubrication

Compressor

model

Swept volume Displacement Oil charge Net weight

cu.in/revMin speed 30 Hz 60 Hz Max speed

oz lb900 rpm 1800 rpm 3600 rpm 6000 rpm

VRJ028 1.64 51 103 206 352 36 68VRJ035 2.12 66 133 265 442 45 71VRJ044 2.65 83 166 332 553 45 71

Compressor specifications

For dedicated Inverter drive specifications, refer to Trane Inverter drive operating instructions.

A specific oil pump ensures optimal bearing lubrication at all compressor speeds. This to have sufficient bearing lubrication at low speeds as well

as avoid excessive Oil Circulation Ratio (OCR) at high speeds.

Model Mode of operation

Condition Speed Combined w/PFC and no PFC Cap Power

TSs/TDs RPM Efficiency Btu/hr W

VRJ028TK

A/C

45/100 3600 70.8 37007 195550/115 3600 79.2 37101 237655/100 1800 71.1 21598 89255/90 900 61.1 10671 386

Heating

30/115 6000 57.8 41269 43095/100 6000 53.8 25971 3707

25/100 2400 66.5 15947 133135/95 900 52.9 6954 495

VRJ034TK

A/C

45/100 3600 72.0 46635 242350/115 3600 65.9 46834 295755/100 1800 69.6 27491 116055/90 900 59.7 13983 517

Heating

30/115 6000 58.8 52394 53765/100 6000 54.9 32855 4593

25/100 2400 67.2 20302 167535/95 900 51 9002 663

VRJ044TK

A/C

45/100 3600 71.7 59925 312550/115 3600 65.3 60112 382555/100 1800 70.2 35597 149055/90 900 59.9 18192 670

Heating

30/115 6000 59.1 67660 69105/100 6000 56.9 43116 5828

25/100 2400 68.5 26347 213235/95 900 51 11577 854

Conditions Evaporating Temperature

(°F)

Condensing Temperature

(°F)Superheat

(°F)Subcooling

(°F)

High SEER conditions (H) 50 115 20 15CHEER conditions 45 100 20 15

Heat Pump conditions 30 110 20 15SEER conditions (I) 55 100 20 15

* Note: The above table shown reflects data from Trane coefficients tested in Trane facility


7FRCC.PC.031.A2.22

Dimensions

VRJ-T 028 - 035 - 044

Mounting grommet will not be provided by Danfoss

7.491-7.509(190.25-190.75)

7.491-7.509(190.25-190.75)

14.19(360.4)

9.07(230.5)

1.771(44.98)

1.598 ±0.059(40.58 ±1.50)

2.090(53.08)

1.859(47.21)

1.936 ±0.059(39.01±1.50)

1.45-1.51(36.6-38.6)

2.95-3.06(74.7-77.7)

EMI bracket

0.43(11.0)

Baseline

Suction line0.753-0.757(19.13-19.23

Discharge line0.502-0.506(12.75-12.85)

15.91(404.0)15.91

(404.0)

Overall height: top of lifting lug of top of sensor bracket

9.40(238.8)

3.750(95.25)

4x Ø10.75-0.78(4x Ø19.0-20.0)

Ø6.438-6.515(Ø163.50-165.50)

9.40(238.8)

3.750(95.25)4.32

(109.7)

5.10(129.6)

4.38(111.3)

2.74-2.81(69.6-71.6)

34° 31°

45° ±2°

14° ±2°

All dimensions in inch (mm)


8 FRCC.PC.031.A2.22

Electrical data, connections and wiring

Supply Voltage VRJ-T compressors must not be connected directly to AC (alternating current) power source. They must only be powered through the dedicated Trane Inverter drive.

Refer to Trane Inverter drive operating instruc-tions for more details about supply voltage.Voltage: 420 max. DCV

Compressor electrical specifications Compressor model

LRA MCC Winding resistanceA A Ohm

VRJ028 10.2 18 0.255VRJ035 12 23.5 0.210VRJ044 12 30 0.210

See below section regarding “Winding resistance” for measurement method

LRA (Locked Rotor Amp)

MCC (Maximum Continuous Current)

Winding resistance

Wiring connections

LRA is the higher average current as measured on a mechanically blocked compressor tested under nominal voltage. LRA is printed on the name-plate, according to UL requirements. With VRJ-T

compressors, the LRA value can not be reached because the Inverter drive will cut-out the supply voltage before.

The MCC value is the maximum at which the com-pressor can be operated in transient conditions and out of the operating envelope. The tripping

current of external over-current protection must never exceed the MCC value.

VRJ-T scroll compressors are equipped with an IPM (permanent magnet) motor.

Winding resistance is the resistance between indi-cated terminal pins at 77°F (resistance value ± 7%).

Winding resistance is generally low and it requires adapted tools for precise measurement. Use a digital ohm-meter, a ‘4 wires’ method and measure under stabilised ambient temperature. Winding resistance varies strongly with winding tempera-ture ; If the compressor is stabilised at a different value than 77°F, the measured resistance must be corrected with following formula:

Rtamb= R77°F

a + t amb

a + t77°F

t77°F: reference temperature = 77°F

t amb : temperature during measurement (°F)

R77°F : winding resistance at 77°F

Rtamb : winding resistance at tamb

a: Coefficient a= 390

VRJ-T scroll compressors will only compress gas while rotating counter-clockwise (when viewed from the compressor top).The drawing shows electrical terminal labelling and should be used as a reference when wiring the compressor.U, V & W of the drive and the compressor must be connected accordingly.

For use of EMI bracket with shielded cable, it is recommended to have a thread cutting screw (#10-32) having a torque of 25 to 30 in-lbs.


9FRCC.PC.031.A2.22

Electrical data, connections and wiring

Terminal cover mounting The terminal cover and gasket should be installed prior to operation of the compressor. The terminal cover has two outside tabs, 180 degrees apart, that

engage the terminal fence. When installing the cover, check that it is not pinching the lead wires.

Terminal cover removal

Internal motor protection

Phase sequence and reverse rotation protection

IP rating

VRJ-T scroll compressors are not equipped with an internal motor protector. Motor protection is pro-vided by the Inverter drive. All motor parameters

are factory preset in order to guarantee optimal locked rotor or overload current protection.

The compressor will only operate properly in a single direction. If electrical connections are done correctly between the drive and the compressor terminals (compressor and drive terminals U, V & W matching), the drive will provide correct phase supply to the compressor, and reverse rotation will be not possible.

If compressor and drive U, V & W terminals are not matching, the compressor can operate in reverse

rotation. This results in excessive noise, no pressure differential between suction and discharge, and suction line warming rather than immediate cooling. The compressor can be rapidly severely damaged in these conditions.

The compressor terminal box IP rating according to CEI 529 is IP22 for all models. This IP rating is only valid when correctly sized cable glands with the same IP rating are applied.

• First numeral, level of protection against contact and foreign objects 2 protection against object size over 1/2 inch (fingers of similar)

• Second numeral, level of protection against water 2 protection against dripping water when tilted up to 15°

push

push

push


10 FRCC.PC.031.A2.22

Approvals and certificates

Approval and certificates VRJ-T scroll compressors comply with the following approvals and certificates.

Pressure equipment directive 97/23/EC

Internal free volumeProducts Internal free volume at LP side without oil (in.3)

VRJ-T 028 - 035 - 044 179

Refrigerating fluids Group 2

Category PED I

Evaluation module no scope

UL (Underwriters Laboratories) All models

Other approvals / certificates Contact Danfoss


11FRCC.PC.031.A2.22

Operating conditions

Refrigerant and lubricants

Motor supply

Compressor ambient temperature

General information

High ambient temperature

PVE

Low ambient temperature

Residual moisture

When choosing a refrigerant, different aspects must be taken into consideration:• Legislation (now and in the future)• Safety• Application envelope in relation to expected

running conditions• Compressor capacity and efficiency• Compressor manufacturer recommenda-

tions & guidelines

Additional points could influence the final choice:• Environmental considerations• Standardization of refrigerants and

lubricants• Refrigerant cost• Refrigerant availability

In case of enclosed fitting and high ambient temperature, it is recommend to check the tem-

perature of power wires and conformity to their insulation specification.

Polyvinyl ether (PVE) is an innovative refrigeration lubricant for HFC refrigerant systems. PVE is as hy-groscopic as existing polyolester lubricants (POE), but PVE does not chemically react with water; no acids are formed and compressor evacuation is easier.

The compressor technology applied in Danfoss Inverter Scroll compressors in combination with PVE lubricant provides the best possible result in terms of reliability and compressor lifetime.

Although the compressor itself can withstand low ambient temperature, the system may require specific design features to ensure safe

and reliable operation. See below sections for recommendations.

Prior to shipment from the factory, every com-pressor is dehydrated, evacuated, and charged with dry nitrogen. Maximum residual moisture

levels are 0.0082 oz. for model VRJ028, and 0.0120 oz. for VRJ035 and VRJ044.

VRJ-T scroll compressors can be operated only connected to the dedicated Inverter drive, at volt-age as indicated in “supply voltage” section.

VRJ-T scroll compressors can be applied from -40°F to 125°F ambient temperature. The compressors are designed as 100 % suction gas

cooled without need for additional fan cooling. Ambient temperature has very little effect on the compressor performance.

VRJ-T scroll compressor application range is in-fluenced by several parameters which need to be monitored for a safe and reliable operation.

These parameters and the main recommenda-tions for good practice and safety devices are explained hereunder:

Refrigerant and lubricantsMotor supplyCompressor ambient temperature

Application envelope (evaporating tempera-ture, condensing temperature, return gas temperature).


12 FRCC.PC.031.A2.22


The operating envelope for VRJ-T scroll com-pressors is given in the figure below, where the condensing and evaporating temperatures repre-sent the range for steady-state operation. Under transient conditions, such as start-up and defrost for heat pump applications, the compressor may operate outside this envelope for short periods.

The operating limits serve to define the envelope within which reliable operations of the compres-sor are guaranteed:

• Maximum dome temperature: +285F• A suction superheat below 9 °F is not recom-mended due to the risk of liquid flood back• Maximum superheat of 40°F• Minimum and maximum evaporating tem-perature and compressor run current, as per the operating envelopes.

All the below limits, temperatures and speeds, are secured by the parameters in the drive and application controller software’s.

The discharge temperature depends mainly on the combination of evaporating tempera-ture, condensing temperature and suction gas superheat and speed. Discharge gas temperature is controlled with a dome temperature sensor

mounted in the provided housing on top of the compressor shell. Maximum discharge gas temperature must not exceed 285°F when the compressor is running within the approved oper-ating envelope.

Application envelope

Maximum discharge gas temperature

2

6

10

14

18

22

26

30

34

38

42

46

50

54

58

62

66

70

35

45

55

65

75

85

95

105

115

125

135

145

155

-40 -30 -20 -10 0 10 20 30 40 50 60 70 80

(°C)

Satu

rate

d c

ond

ensi

ng t

emp.

(°F)

Saturated evaporating temp. (°F)

VRJ-T Operating Envelope 900-6000RPM

900-6000 RPM

1100-5400 RPM1300-4800 RPM

1500-4200 RPM

1800-3600 RPM2100-3000 RPM

2400 RPM

(°C)


13FRCC.PC.031.A2.22


Pressure settings

High pressure

Low pressure

High pressure ratio

Crankcase heating

Oil return management

R410AWorking pressure range high side psig 119 / 645Working pressure range low side psig 17 / 202Maximum high pressure safety switch setting psig 650Minimum low pressure safety switch setting psig 13.3Maximum testing pressure psig 650

LP safety switch shall never be bypassed

According to UL requirements, a high pressure safety switch is still mandatory in any system, even with high pressure transmitters connected and used via the Inverter drive.

HP switch settings shall not exceed the maximum service pressure of any system components. The high-pressure switch can be set to lower values

depending on the application and ambient con-ditions. The HP switch must either be placed in a lockout circuit or consist of a manual reset device to prevent cycling around the high-pressure limit. If a discharge valve is used, the HP switch must be connected to the service valve gauge port, which must not be isolated.

A low pressure (LP) safety switch is recom-mended. Deep vacuum operations of a scroll compressor can cause internal electrical arcing and scroll instability. Danfoss scroll compressors exhibit high volumetric efficiency and may draw very low vacuum levels, which could induce such a problem. The minimum low-pressure safety

switch (loss of charge safety switch) setting is giv-en in the above table. Either the LP safety switch must be a manual lockout device or an automatic switch wired into an electrical lockout circuit. The LP switch tolerance must not allow for vacuum operations of the compressor.

Scroll compressors are machines with fixed volume ratio, and operate more efficiently near the design pressure ratio. In the extreme, do not exceed a 7.5:1 pressure ratio (absolute discharge pressure to absolute suction pressure) for extend-

ed periods. The VRJ scroll compressor is equipped with an internal pressure relief valve for protec-tion against blocked condenser and fan failure conditions.

A crankcase heating function can be provided by injecting a DC current in the motor of the com-

pressor, to keep the compressor warm, and avoid liquid migration during off cycle.

A specific function is enabled to secure the oil return to the compressor. When the compres-sor is running below 2400 rpm for extended

periods, every 19 min, speed will be increased to 2400 rpm for a 60 second period. Compressor then ramps to demand speed at 0.25hz/sec.

Suction pressure transmitter must be installed and connected to the Inverter drive to ensure the compressor operates within the application envelope described above.

High pressure application envelope protection is achieved through compressor current and dome temperature algorithms.

High and low pressure protection


14 FRCC.PC.031.A2.22


Start-up sequence To ensure correct lubrication of all the mechani-cal parts, VRJ-T compressors start with a defined ramp-up, and stay at a fixed speed of 2400rpm for 60s seconds. Then the compressor speed increases or decreases to the desired set point

according to capacity request. Compressor ramps from standstill to 440rpm at 50hz/sec. After that it ramps from 440rpm to 2400rpm at 2.6hz/sec

On/off cycling (cycle rate limit)

The on/off cycling protection is included in the Inverter drive. There is no need for extra on/off cycling protection.


15FRCC.PC.031.A2.22

System design recommendations

Proper piping practices should be employed to ensure adequate oil return, even under minimum load conditions with special consideration given to the size and slope of the tubing coming from the evaporator. Tubing returns from the evapora-tor should be designed so as not to trap oil and to prevent oil and refrigerant migration back to the compressor during off-cycles.

It is particularly important and critical with vari-able capacity systems, where very low velocities can be achieved for long periods of time, gener-ating oil return issues.

If the evaporator lies above the compressor, as is often the case in split or remote condenser systems, the addition of a pump-down cycle is strongly recommended. If a pump-down cycle were to be omitted, the suction line must have a loop at the evaporator outlet to prevent refrig-erant from draining into the compressor during offcycles.

If the evaporator were situated below the com-pressor, the suction riser must be trapped so as to prevent liquid refrigerant from collecting at the thermal bulb location (see fig. 1).

When the condenser is mounted at a higher

position than the compressor, a suitably sized «U»-shaped trap close to the compressor is necessary to prevent oil leaving the compressor from draining back to the discharge side of the compressor during off cycle. The upper loop also helps avoid condensed liquid refrigerant from draining back to the compressor when stopped (see fig. 2). The max elevation is dependent on vapor line diameters used. The elevation can exceed 25ft in some cases but they are specific vapor line diameters. Following are vapor line diameters that are approved by Trane Residential for elevations upto 25ft in heat pump applica-tions. 2T-3/4’’, 3T,4T & 5T-7/8’’

Piping should be designed with adequate three-dimensional flexibility. It should not be in contact with the surrounding structure, unless a proper tubing mount has been installed. This protection proves necessary to avoid excess vibration, which can ultimately result in connec-tion or tube failure due to fatigue or wear from abrasion. Aside from tubing and connection damage, excess vibration may be transmitted to the surrounding structure and generate an unac-ceptable noise level within that structure as well (for more information on noise and vibration, see the section on: “Sound and vibration manage-ment” section.

Essential piping design considerations

Successful application of scroll compressors is dependent on careful selection of the compres-sor for the application. If the compressor is not correct for the system, it will operate beyond the

limits given in this manual. Poor performance, reduced reliability, or both may result.

General

0.5 % slope,13 ft/s or more

0.5 % slope,13 ft/s or more

�g.1

26 to 40 ft/s

To condenser

Evaporator

Condenser

HP

3D flexibility

Upper loop

LP

fig. 2

Note: Trane Residential does not specify a trap or U-shaped trap on their line set requirements


16 FRCC.PC.031.A2.22


Reversible heat pump systems

Minimum sump superheat

Preventing liquid flood back

Transients are likely to occur in reversible heat pump systems, i.e. a changeover cycle from cool-ing to heating, defrost or low-load short cycles. These transient modes of operation may lead to liquid refrigerant carryover (or flood back) or excessively wet refrigerant return conditions. As such, reversible cycle applications require specific

precautions for ensuring a long compressor life and satisfactory operating characteristics. Spe-cific tests for repetitive flood back are required to confirm whether or not special system design considerations should be considered.

The minimum sump temperature is in the range from 10°F to 30°F above saturated suction tem-

perature. Refer to the flood back test criteria.

Danfoss recommends the use of an electronic expansion valve for all air conditioning and heat pump applications with VRJ-T compressors. An EXV has two key benefits: it provides modulat-ing control of the system under varying load

conditions, and it protects the compressors from flood back during adverse running conditions.Ex-ceptions to the use of EXV’s with Danfoss Inverter VRJ-T must be approved by Danfoss application engineering.

Scroll compressors can tolerate liquid refrigerant up to a certain extend without major problems. However, excessive liquid refrigerant in the compressor is always unfavourable for service life. Besides, the installation cooling capacity may be reduced because of the evaporation taking

place in the compressor and/or the suction line instead of the evaporator. System design must be such that the amount of liquid refrigerant in the compressor is limited. In this respect, follow the guidelines given in the section: “Essential piping design recommendations” in priority.

Refrigerant charge limit

0

5

10

15

20

25

30

35

40

-40 -30 -20 -10 0 10 20 30 40 50 60 70

Sum

p Su

perh

eat,

°F

Saturated Suction, °F

Floodback Requirement


17FRCC.PC.031.A2.22


Oil level checking and top-up

Loss of charge protection

In installations with good oil return and line runs up to 150 ft, no additional oil is required. If installation lines exceed 150 ft, additional oil may be needed. 1 or 2% of the total system refrigerant charge (in weight) can be used to roughly define the required oil top-up quantity.

Always use oil from new cans.Top-up the oil while the compressor is idle. Use any accessible connector on the compressor suction line and a suitable pump.

VRJ-T scroll compressors together with the Inverter drive include a loss of charge protection function. This protection is ensured if pressure

and temperature sensors are connected to the drive.


18 FRCC.PC.031.A2.22

Sound and vibration management

Running sound level

Stopping sound level

Sound generation in a refrigeration system and air conditioning system

During start-up transients, it is natural for the compressor sound level to be slightly higher than during normal running. Danfoss scroll compres-

sors exhibit very little increased start-up transient sound.

VRJ-T scroll compressors are designed with optimized discharge ports and wrap geometry

to reduce the sound level when a compressor is running.

VRJ-T scroll compressors have very low shutdown sound due to minimal volume of discharge vol-ume to push scrolls in reverse at shutdown. Due

to this small re-expansion, there is no internal break mechanism required to prevent reverse spin of the scroll set.

Typical sound and vibration in refrigeration and air conditioning systems encountered by design and service engineers may be broken down into the following three source categories.Sound radiation: This generally takes an air-borne path.

Mechanical vibrations: These generally extend along the parts of the unit and structure.Gas pulsation: This tends to travel through the cooling medium, i.e. the refrigerant.The following sections will focus on the causes and methods of mitigation for each of the above sources.

Starting sound level

The VRJ-T exhibits a pulsing or tapping sound at system pressure ratios below 1.8 and is increas-ingly noticeable below 3000 RPM. This sound is normal and does not indicate compressor mal-

function. LPR sound will dissipate with increase in system pressure ratio or rpm.

LPR sound level

60.0

65.0

70.0

75.0

80.0

85.0

0 20 40 60 80 100 120

Sou

nd-d

BA

Compressor Speed - rps or Hz50/80 50/80 50/80 50/80 50/80 50/80


19FRCC.PC.031.A2.22

Sound and vibration management

Gas pulsation

Electro Magnetic Interference (EMI)

Mechanical vibrations

The VRJ-T scroll compressor has been designed and tested to ensure that gas pulsation has been optimised for the most commonly encountered air conditioning pressure ratio. On heat pump installations and other installations where the pressure ratio lies beyond the typical range, testing should be conducted under all expected

conditions and operating configurations to en-sure that minimum gas pulsation is present. If an unacceptable level is identified, a discharge muf-fler with the appropriate resonant volume and mass should be installed. This information can be obtained from the component manufacturer.

Electro-Magnetic Interference (EMI), is generated within the compressor drive and can be radiated from the compressor wire harness. EMI has the potential to create interference of other electron-ic devices such as televisions, radios, baby moni-tors, cell phones, etc. The VRJ-T scroll compressor and drive combination have been designed

for reduced radiated EMI by application of a shielded compressor wire harness which must be electrically grounded at both ends (drive and and compressor end). Compressor is provided with an EMI bracket beneath the hermetic terminal fence for termination of the harness shielding.

Vibration isolation constitutes the primary meth-od for controlling structural vibration. VRJ-T scroll compressors are designed to produce minimal vibration during operations. The use of rubber isolators on the compressor base plate is very effective in reducing vibration being transmit-ted from the compressor to the unit. Once the rubber isolators or grommets have been properly mounted, vibrations transmitted from the com-pressor base plate to the unit are held to a strict minimum. In addition, it is extremely important that the frame supporting the mounted com-pressor be of sufficient mass and stiffness to help dampen any residual vibration potentially trans-mitted to the frame. The rubber isolators and tubing should be designed so as to both reduce

the transmission of vibrations to other structures and withstand vibration without incurring any damage. Tubing should also be designed for three-dimensional flexibility.

During unit development, the complete com-pressor speed range should be covered, in order to define if abnormal vibrations occur or not. As ultimate solution, speed bypass can be applied.

For more information on piping design, please see the section entitled “Essential piping design considerations”.

Compressor sound radiation For sound radiating from the compressor, the emission path is airborne and the sound waves are travelling directly from the machine in all directions.The VRJ-T scroll compressor is designed to be quiet and the frequency of the sound generated is pushed into the higher ranges, which not only are easier to reduce but also do not generate the penetrating power of lower-frequency sound.Use of sound-insulation materials on the inside of unit panels is an effective means of substantially

reducing the sound being transmitted to the outside.Ensure that no components capable of transmit-ting sound/vibration within the unit come into direct contact with any non-insulated parts on the walls of the unit.Because of the Danfoss unique design of a fullsuction gas & oil cooled motor, compressor body insulation across its entire operating range is possible.


20 FRCC.PC.031.A2.22

Installation

System cleanliness

Compressor handling and storage

Compressor mounting

Compressor holding charge

Tube brazing procedure

Brazing material

Each VRJ-T scroll compressor is shipped with printed Instructions for installation.

The refrigerant compression system, regardless of the type of compressor used, will only provide high efficiency and good reliability, along with a long operating life, if the system contains solely the refrigerant and oil it was designed for. Any other substances within the system will not improve performance and, in most cases, will be highly detrimental to system operations.

The presence of non-condensable substances and system contaminants, such as metal shav-ings, solder and flux, has a negative impact on compressor service life. Many of these contami-nants are small enough to pass through a mesh screen and can cause considerable damage within a bearing assembly. The use of highly hy-groscopic PVE oils in R410A compressors requires that the oil be exposed to the atmosphere as little as possible.

System contamination is one of main factors affecting equipment reliability and compressor service life. It is important therefore to take sys-tem cleanliness into account when assembling a refrigeration system.

During the manufacturing process, circuit con-tamination may be caused by:• Brazing and welding oxides,• Filings and particles from the removal of burrs in pipe-work,• Brazing flux,• Moisture and air.

Consequently, when building equipment and assemblies, the following precautions must be taken: never drill holes into the pipe-work after installation.

Compressors are provided with a lifting lug. This lug should always be used to lift the compres-sor. Once the compressor is installed, the lifting lug should never be used to lift the complete installation.

The compressor must be handled with caution in the vertical position, with a maximum inclina-tion of 15° from vertical. Store the compressor between -40°F and 125°F, not exposed to rain or corrosive atmosphere. Care must be taken to avoid contact or damage to dome sensor or housing on top of compressor.

Maximum inclination from the vertical plane, while operating must not exceed 7 degrees.

Compressors must always be mounted with grommets.

Each compressor is shipped with a nominal dry nitrogen holding charge between 6 psi and 10 psi, and is sealed with elastomeric plugs. The plugs should be removed with care to avoid oil loss when the holding charge is released. Remove the suction plug first and the discharge plug

afterwards. The plugs shall be removed only just before connecting the compressor to the installation in order to avoid moisture entering the compressor. When the plugs are removed, it is essential to keep the compressor in an upright position to avoid oil spillage.

Do not bend the compressor discharge or suction lines or force system piping into the compressor connections, because this will increase stresses

that are a potential cause of failure. Recom-mended brazing procedures and material, are described on following page.

For copper suction and discharge fittings, use copper-phosphorus brazing material. Sil-Fos® and other silver brazing materials are also acceptable.

If flux is required for the brazing operation, use coated rod or flux core wire. To avoid system contamination, do not brush flux on.


21FRCC.PC.031.A2.22

Installation

Vacuum evacuation and moisture removal

When brazing the compressor fittings, do not overheat the compressor shell, which could se-verely damage certain internal components due to excessive heating. Use of a heat shield and/or a heat-absorbent compound is highly recom-mended. For brazing the suction and discharge connections, the following procedure is advised:• Make sure that no electrical wiring is connected to the compressor.• Protect the terminal box and compressor painted surfaces from torch heat damage (see diagram).• Use only clean refrigeration-grade copper tub-ing and clean all connections.• Purge nitrogen or CO2 through the compressor in order to prevent against oxidation and flam-mable conditions. The compressor should not be exposed to the open air for extended periods.• Use of a double-tipped torch is recommended.• Apply heat evenly to area A until the brazing temperature is reached. Move the torch to area B and apply heat evenly until the brazing tempera-ture has been reached there as well, and then be-gin adding the brazing material. Move the torch evenly around the joint, in applying only enough brazing material to flow the full circumference of the joint. • Move the torch to area C only long enough to draw the brazing material into the joint, but not into the compressor.• Remove all remaining flux once the joint has been soldered with a wire brush or a wet cloth. Remaining flux would cause corrosion of the tubing.

Ensure that no flux is allowed to enter into the tubing or compressor. Flux is acidic and can cause substantial damage to the internal parts of the system and compressor.

The PVE oil used in VRJ-T compressors is highly hygroscopic and will rapidly absorb moisture from the air. The compressor must therefore not be left open to the atmosphere for a long period of time.

The compressor fitting plugs shall be removed just before brazing the compressor. Before eventual unbrazing the compressor or any system component, the refrigerant charge must be removed from both the high and low pressure sides. Failure to do so may result in serious personal injury. Pressure gauges must be used to ensure all pressures are at atmospheric level.

For more detailed information on the appropriate materials required for brazing or soldering, please contact the product manufacturer or distributor. For specific applications not covered herein, please contact Danfoss Commercial Compressors for further information.

Moisture obstructs the proper functioning of both the compressor and the refrigeration system.

Air and moisture reduce service life and increase condensing pressure, which causes abnormally high discharge temperatures that are then ca-pable of degrading the lubricating properties of the oil. The risk of acid formation is also increased by air and moisture, and this condition can also lead to copper plating. All these phenomena may

cause both mechanical and electrical compressor failures. The typical method for avoiding such problems is a vacuum pump-down executed with a vacuum pump, thus creating a minimum vacuum of 0.02 in Hg (500 μm Hg). Please refer to Bulletin “Vacuum pump down and dehydration procedure”.

Be sure to follow all government regulations regarding refrigerant reclamation and storage.

Compressor connectionHeat shield

C B A


22 FRCC.PC.031.A2.22

Installation

Liquid line filter driers A properly sized filter drier is required for all Danfoss scroll applications. Danfoss recommends DML (100% molecular sieves) driers for HFC refrigerants R410A with PVE oil. For servicing of existing installations where acid formation is present the Danfoss DCL solid core filter driers

containing activated alumina are recommended. The drier is to be over sized rather than under sized. When selecting a drier, always take into account its capacity (water content capacity), the system refrigeration capacity and the system refrigerant charge.

Refrigerant charging

Insulation resistance and dielectric strength

Compressor replacement after motor burn out

It is recommended that system charging be done using the system sub-cooling charge method, adding refrigerant to the high side of the system (see system installation instructions). Charging the high and low sides of a system with gas simultaneously at a controlled rate is also an

acceptable method.

Never exceed the recommended system charge mentioned by the unit manufacturer, and never charge liquid to the low pressure side.

Insulation resistance must be greater than 1 megohm when measured with a 500 volt direct current megohm tester.

Each compressor motor is tested at the factory with a high potential voltage (hi-pot) that ex-ceeds the UL requirement both in potential and in duration. Leakage current is less than 0.5 mA.

VRJ-T scroll compressors are configured with the pump assembly at the top of the shell, and the motor below. As a result, the motor can be partially immersed in refrigerant and oil. The presence of refrigerant around the motor

windings will result in lower resistance values to ground and higher leakage current readings. Such readings do not indicate a faulty compres-sor, and should not be cause for concern.

In testing insulation resistance, Danfoss recom-mends that the system be first operated briefly to distribute refrigerant throughout the system. Fol-lowing this brief operation, retest the compressor for insulation resistance or current leakage.

If there has been a motor burnout follow the evacuation procedure described on previous page. Remove and replace the liquid line filter drier and install a Danfoss type DAS burnout drier of appropriate capacity.

Refer to the DAS drier instructions and technical information on correct use and monitoring of the burnout drier and the liquid line and suction line filter driers.


23FRCC.PC.031.A2.22

Ordering information and packaging

Packaging

Single pack Compressors are packed individually in a card-board box. They can be ordered in any quantity. Minimum ordering quantity = 16

All single packs are packaged in a ISTA-1A ap-proved carton.

Returnable pallet

Ordering code numbers

Accessory

Compressors are not packed individually but are shipped all together on one pallet. They can be ordered in quantities of full pallets only, multiples 16 compressors.

Empty pallets must be returned to the compres-sor factory.

Returnable pallets contain neither rubber grom-mets, nor sleeves.

Compressor model Qty of compressors

3 Tons 4 Tons 5 TonsVRJ028 VRJ035 VRJ044

Code number

Single pack 1 120U7019 120U7021 120U7023

Returnable pallet 16 120U7018 120U7020 120U7022

Type Code n° Description Application Packaging Pack size

120Z5066 Terminal kit box VRJ-T: terminal cover + gasket all models VRJ-T multipack 24

Description Part no Quantity1) Terminal cover 7SC5410D0A 242) Terminal gasket 7SC5411C04 24

Danfoss Commercial Compressors is a worldwide manufacturer of compressors and condensing units for refrigeration and HVAC applications. With a wide range of high quality and innovative products we help your company to find the best possible energy efficient solution that respects the environment and reduces total life cycle costs.

We have 40 years of experience within the development of hermetic compressors which has brought us amongst the global leaders in our business, and positioned us as distinct variable speed technology specialists. Today we operate from engineering and manufacturing facilities spread across three continents.

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FRCC.PC.031.A2.22 - December 2014 - Replaces FRCC.PC.031.A1.22 - April 2014 © Copyright Danfoss | Commercial Compressors | 2014.12

Our products can be found in a variety of applications such as rooftops, chillers, residential air conditioners, heatpumps, coldrooms, supermarkets, milk tank cooling and industrial cooling processes.

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Danfoss Commercial Compressors, BP 331, 01603 Trévoux Cedex, France | +334 74 00 28 29

Documents

Application guidelines - Danfossfiles.danfoss.com/TechnicalInfo/Dila/17/FRCC.PC.031.A2.22-VRT... · Danfoss Inverter Scrolls R410A Tailored for Trane Residential use only Application