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Plant SeriesSECTION 024-460 -10l%@

Issue 1, Septemberr 1931

VOLTAGE REGULATORSAT&TCo Standard

AC-DC AUTOMATIC ROTATING CAM TYPES

DESCRIPTION

1. GENERAL

1.01 This section covers the a-c. and cl-c. auto-matic rotating cam type voltage regulators

per KS-5016 and KS-5 117 used for automaticallyregulating the voltage of battery charging gen-erators in telephone power plants.

1.02 Each automatic rotating cam type voltageregulator consists of a voltage control coil

and plunger operating a balanced contact arm tomake and break auxiliary circuits through a motor-driven rotating contact cam, thereby controlling amotor-driven rheostat in a generator field. Atapped controller coil resistance, together with anadjustable controller coil resistance, is provided inseries with the voltage control coil to permit thevoltage regulation of generators connected to bat-teries of 49.5, 25 and 23.5 volts approximately,while a compensating rheostat, adjustable fromthe control panel, is also provided in this circuit toshift the operating voltage range by small amountsto get the exact setting desired. The entire set ofapparatus is mounted on a panel enclosed in ametal cabinet.

1.03 The automatic rotating cam type voltageregulators are designed for operation on

either a-c. or d-c. power or lighting circuits. Thevoltage regulation limits are set to meet the re-quirements of the particular installation.

1.04 The automatic rotating cam type voltageregulator includes a combination of the fol-

lowing major parts.

Voltage Relay Assembly

Motor-Driven Rheostat Assembly

Rheostat Motor Contractors

1.05 The earlier KS-5016 regulator used a hori-zontal disc with one cam on top and one on

the bottom driven at 6 rpm by a series commu-tator type motor. In the later KS-5117 regulatorsa vertical disc with 6 cams driven at 1 rpm by asynchronotls -type motor is employed where a-c.power is available. For the few installations us-ing d-c. power, the KS-51 17 regulator retains theseries commutator type motor driving a horizontalcam.

volts(with

gew

Relay Assembly-‘arren Motor)

Rheostat Motor-Contactor

,,”

‘*

Fig. l—A-C. Automatic Rotating Cam Type Voltage Regulator(KS-5117, Front View Shown)

.Motor-DrivenRheostat Assembly

f’-Copyright, 1931, by American Telephone and Telegraph Company

Printed in U. S. A.Page 1

0-.

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Fig. 2—A-C. Automatic Rotating Cam Type Voltage Regulator(KS-51 17, Rear View Shown)

Voltage Relay Assembly(with Series D-C. Motor)

Rheostat MotorContactor

Motor-DrivenAssembly

Rh.eostat

Fig. 3—D-C. Automatic Rotating Cam Type Voltage Regulator(KS-5117)

Page 2

Voltage Relay Assembly(with Series D-C. Motor)

.Rheostat MotorContactor

1SS 1, SECTION 024-460-10 i

Fig. 4-D-C. Automatic Rotating Cam Type Voltage Regulator(KS-5016)

loltage Relay Assembly(with Series A-C. Motor)

.

Rheostat MotorContactor

.

Motor-DrivenRheostat ASSC

Motor-DRheostat

Fig. 5—A-C. Automatic Rotating Cam Type Voltage Regulator(KS-5016)

Iriven

IIy

!mbly

Page 3

SECTION 024-460-101

2. DESCRIPTION OF APPARATUS

Voltage Relay Assembly

2.01 The voltage relay assembly of the automaticrotating cam type voltage regulator consists

of a voltage control coil and plunger, the balancedarm with spring contacts and adjusting springand the rotating contact cam with its driving mo-tor.

2.02 Voltage Control Coil: The voltage controlcoil (solenoid type) consists of a single

winding connected across the points at which thevoltage is to be regulated. Within this coil is amovable iron plunger which is attached to oneend of the balanced arm. The voltage control coilis mounted vertically on the supporting panel. Aguide pin is located in the lower end of the plunger,sliding in a guide pin bushing to keep the plungercentrally located within the coil.

2.03 Voltage Control Coil Resistances: In serieswith the voltage control coil are several re-

sistances used both to compensate for manufactur-ing variations and to adapt the regulator for useon any one of three voltages.

(a) Tapped controller coil resistance: A con-troller coil resistance of the tapped tubu-

lar type adapts the regulator for use with thenominal 48 volt battery (49.5 volt—terminal2). A tap using part of this resistance istaken off for the 24 volt battery when floating11 cells. (23.5 volt—terminal 4).

(b) Adjustable controller coil resistance: Anadditional adjustable resistance is in se-

ries with this central tap 4 to adapt the regu-lator either for floating 12 cells or constantvoltage charging 11 cells (25 volt—terminal3). This resistance is provided to enable thefactory to exactly and permanently adjust theratio of the 25 volt tap to the 23.5 volt tap.

(c) Compensating Rheostat: In addition tothese resistances, which when once set

are ordinarily not altered, there is provided inseries with the voltage control coil a com-pensating rheostat to make it possible to shiftthe voltage regulating point a small amountin either direction to obtain the exact voltagedesired. This compensating rheostat is con-nected next to the coil and affects all of thethree taps listed below.

Controller Nominal VoltageCoil Taps Setting

1-4 23.51-3 25.1-2 49.5

This rheostat also performs an importantfunction in compensating for the voltage dropin the leads from the regulated point to thevoltage control coil which requires consider-able current. It also compensates for tem-perature differences in the voltage control

Page 4

coil for winter and summer. A total compen-sation up to 2.5 volts is provided.

All of these resistances are mounted on therear of the regulator control panel. The com-pensating rheostat is adjustable from the frontof the panel by a removable tool in earliermodels or by a screw driver in later models -and is provided with a nameplate indicatingthe proper direction to raise or lower thevoltage at which the regulator functions.

2.04 Balanced Contact Arm and Spring Con-i

tacts: The balanced contact arm fromwhich the voltage control coil plunger and contactsprings are suspended, is made of aluminum andmounted on two hard steel pivot bearings to re-

.

duce its inertia and increase its sensitivity. Thebearings are made so as to reduce friction to aminimum and are adjustable horizontally. An ad-justable spiral or helical spring is attached to thevoltage control coil end of the balanced contactarm to support the plunger within the voltage con-trol coil. The movement of the balanced contactarm is limited by an adjustable stop screw ar-rangement. The flat contact springs are adjustedby means of screws, and are insulated from thearm and from each other. The contacts on theflat springs are made of chemically pure silver,having slightly rounded contact surfaces, and areprovided with insulated flexible copper connectorsto carry the current. Mounting the contacts onthe flat springs eliminates chattering contact withthe contact cam.

2.05 Rotating Contact Cam: The rotating con-tact cam is motor-driven through an en-

closed reduction gear unit. The rotating contactcam is mounted on the shaft of the associated gearunit, adjustable axially on, and insulated from theshaft. The cam is provided with a means of lock-ing it in position on the shaft. The contacts ofthe cam are of such size and shape and so spacedthat the ratio of the length of the “ open” to the“ closed” period of the contactor, the operation ofwhich these contacts control, is not less than sixto one wheu the balanced contact arm of the volt-age relay is in such a position as to make thelightest contact between the spring contact andcam contact which will close the. associated motorcontactor positively. The contacts are shaped sothat with the balanced contact arm in either of itsextreme positions of travel, the spring contact willnot catch on the cam contacts so as to cause dam-age to the contacts or mechanism or to stall thecam drive motor. A flat contact spring bearing onthe center of the cam in the case of the a-c. drivenregulator and on the hub of the cam in the case ofthe d-c. driven regulator is used for a connectionto the rotating cam.

2.06 Motors for Driving Rotating Contact Cam:For driving the rotating contact cams of

the regulators, Warren synchronous motors arefurnished for a-c. power service and series d-c.motors for d-c. power service. The Warren mo-

—

1SS 1, SECTION 024-460-101

T

tor used ;S similar in construction to the motor ele-ment used in the commercial Telechron electricclocks. The motor is provided with its own en-closed reduction gear and in case of any troubleis replaced as a unit. No adjustments should bemade on these motors in the field. The d-c. mo-tors are commercial series wound motors. Themotor is provided with bearings of the sleeve typehaving wick Qilers which hang vertically when themotor is mounted on the regulator panel. Thecommutator has segments of hard-drawn copperof ample wearing depth and has insulation be-tween the segments of selected mica, or micanite.The segments are clamped together by means of“ V-shaped “ rings fitted into grooves at the endsof the commutator. The motor brushes are rec-tangular in cross-section, self-lubricating and ofsuch quality as to insure satisfactory operation.The brush holders are of the tubular type. Thebrushes are held in the holders by threaded capscrews, having moulded insulating caps withknurled edges to permit removing the brusheswithout the aid of tools. The motor is mountedso that it can readily be replaced without dis-

~ mounting the regulator panel.

2.07 Reduction Gear Units for Rotating ContactCam: The Warren motor is provided with

the necessary gearing enclosed within the motorhousing so that the shaft on which the rotatingcontact cam is mounted runs at the required speed.The motor housing is sealed so that the oil forthe gearing and bearings does not escape to theoutside of the motor. Where a d-c. motor is used,the reduction gear for the rotating contact cam,except the pinion gear on the motor shaft and thegear associated with it, is totally enclosed in agear case filled with grease. The shaft of thecam driving motor and the reduction gear shaftare properly aligned so that no binding action ofthe mechanism occurs. A grease plug is providedon the front of the gear case. The shafts ~f thereduction gears are provided with a packing ar-rangement to prevent oil leaking along the shaftswhere they extend through the cam gear case.

Motor-Driven Rheostat Assembly

2.08 Rheostat: The automatic rheostat has 120or more steps for all regulators except the

regulator of the generator having a field currenti of more than 35 amperes, in which instance not

less than 100 steps are used. The contacts aremounted so that there are no short circuits be-

; tween adjacent steps. The rheostat is constructedso that different resistances can be applied for dif-ferent charging generators u’ithout changing thegeneral construction of the automatic voltage reg-ulator. The contact brushes on the movable armare self-aligning and designed so that wear willnot cause them to. jam against the rheostat con-tact buttons. Flexlble copper shunts are providedfor good connections between the contact brushesand the rheostat arm.

2.09 Motors for Driving Rheostat: The a-c. andd-c. motors for driving the rheostat are

commercial series-wound motors suitable for op-eration on the power service of the particular in-stallation. Each motor has two field windings toprovide for the rotation of the motor in either di-rection. The motor is equipped with sleeve bear-ings capable of taking the thrust of the drivingworm in either direction. All bearings havewick oilers hanging vertically when the motor ismounted on the regulator. panel. The commuta-tor has segments of hard-drawn copper of amplewearing depth and insulation between the seg-ments of selected mica or micanite. The seg-ments are clamped together by means of “ V-shaped “ rings, fitted into grooves at the ends ofthe commutator. The motor brushes are rectan-gular in cross-section, self-lubricating and of suchquality as to insure satisfactory operation. Thebrush holders are of the tubular type. Thebrushes are held in the holders by threaded capscrews having moulded insulating caps withknurled edges to permit removing the brusheswithout the aid of tools. The motor is mountedso that it can readily be replaced without dis-mounting the regulator panel.

2.10 Reduction Gear for Rheostat: An open re-duction gear unit is used with the motor-

driven rheostat. All of the bearings of the auto-matic rheostat gearing, except the rheostat shaftbearings, are provided with grease cups for properIubriiation. The back lash in the gearing of theautomatic rheostat does not exceed that amountwhich will allow the contact end of the rheostatarm to be moved j4 inch circumferentially at theouter ring of contacts.

2.11 Limit Switches: Limit switches are pro-vided at the two extreme positions of the

rheostat. These switches are connected to openthe holding coil circuits” of the motor contractorsand prevent the rheostat arm from tra$eling pastthe end contact buttons of the rheostat.

,Rheostat Motor Contractors

2.12 The motor contractors are single-pole con-tractors which in closing connect the asso-

ciated rheostat motor directly to the power servicethrough the main contacts of the contactor. Thecoil of the contactor is connected in series withthe spring contacts and rotating contact cam ofthe voltage relay assembly and is energized whenthe associated spring contact makes contact withthe rotating contact cam. The motor contactorhas associated auxiliary contacts, open when themotor contactor is closed and closed when themotor contactor is open. The associated auxiliarycontacts are connected in series with the coil ofthe other motor contactor and act as an electricalinterlock in the circuit.

Page 5

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Fk 6-Schematic Diagram of Connections

Automatic Voltage Regulator with Control Panel for One 33 Volt GeneratorContinuous Floating Routine

1SS 1, SECTION 024-460-101

Associated Equipment

2.13 On each regulator for operation on a-c.power service, the following equipment is

provided for reducing the sparking at the cam andspring contacts. -A condenser having a capacityof at least 2 MF in parallel with each rheostat mo-tor contactor coil. The condensers are mountedso as to permit easy replacement. A resistance of40 ohms and a one-ampere N.E. Code cartiidgetype fuse in series with the common lead furnishcurrent to the coils of the two rheostat motor con-tractors.

3. THEORY OF OPERATION

+’3.01 Compensation for Low Voltage (Refer to

Fig. 6 and Fig. 7): If the voltage at theregulated points drops outside the ‘setting of thevoltage control coil, the control coil plunger willfall causing the lower spring contact to make con-tact with the rotating cam. Whe? the contactsurface of the cam makes contact with the springcontact a circuit is closed from the outside power

service through the rotating cam, the lower springcontact, the auxiliary contacts of the Lower con-tactor, the winding of the Raise contactor and thelimit switch, back to the other side of the powerservice. The Raise contactor is operated whilethe rotating cam and lower spring contact makecontact. The operation of the Raise contactorcloses a circuit from the power service leadsthrough the limit switch, the main contacts of theRaise contactor, one of the rheostat drive motorseries fields, the motor armature, and back to theother side of the power service. This starts therheostat drive motor and cuts out resistance inthe field circuit until the voltage is raised suffi-ciently to break the Raise contactor circuit de-scribed above, due to the operation of the voltagecontrol coil and spring contact, or to the rotationof the contact cam. If due to the latter case, afurther readjustment will be made approximatelyevery ten seconds until the voltage is sufficientlyraised. This interval of delay has been intro-duced to allow time for the voltage of the batteryto which the generator is connected to become

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Notes: 1. Double pole “ Reg. Rheo.” switch mechanically interlocked with 2 single polecircuit maintaining switches.

2. For regulator connections see Fig. 6.

Fig. 7-Schematic Diagram of Connections

Automatic Voltage Regulator with Control Panel for Two 33 or Two 65 Volt GeneratorsContinuous Floating Routine

Peg, 7

SECTION 024-460-101

stable at the new value of charging current.Without the delay, continuous operation of theregulator either up or down, i.e., “ hunting, ‘would be likely to occur. In case the rheostatdrive motor carries the rheostat arm to the end ofits travel in an effort to regulate the voltage, alimit switch will open the circuits of the motorand the Raise contactor, stopping the rheostatdrive motor. The operation of the Raise contactorreferred to above also opens through its auxiliarycontacts the lead from the power service to thewinding of the Lower contactor so that both theRaise and Lower field of the rheostat drive motorcannot be energized at the same time.

3.02 Compensation for High Voltage (Refer toFig. 6 and Fig. 7) : The operation of the

voltage regulator due to high voltage is similar tothe above. The raising of the voltage control coilplunger brings the upper spring contact in contactwith the rotatin~ cam. When the contact cammakes contact with the upper spring contact, thesame circuit from the power line to the rotatingearns described above is closed through the upperspring contact, the auxiliary contacts of the Raisecontactor, the winding of the Lower contactor andthe limit switch, back to the other side of thepou’er service. This operates the Lower con-tactor which energizes the other field of the rheo-stat drive motor through the main contacts of thiscontactor. The rheostat arm is driven in the op-

Page 8

posite direction to that described above in orderto cut in more field resistance and lower the gen-erator voltage. A limit switch is also provided atthis end of the rheostat arm travel which functionssimilar to the description covered in paragraph3.01.

3.03 Table of Resistors: Behind the panel T,

shown in the previous figures, and enclosedin the steel cabinet, are the resistors attached tothe contact buttons on the face plate. These re-sistors are ordinarily connected in series with theshunt fielcl and the field rheostat of the generatorwhich is to be regulated. The automatic regulatorthus acts as an interpolating field rheostat, buthas sui%cient range and resistance to regulate theoutput current of the generator from no load tofull load or through a substantial part of thisrange. In order to assist in the operation of theseregulators by giving information on expectedrange and performance, Table 1 is included, list-ing several of the machines with which this typeof regulator is most commonly employed. It ispracticable to switch the regulator to controleither one of two machines provided their char-acteristics are similar. When, however: it is de-sired to control two machines widely differing inoutput the regulator must generally be se!ectedfor the larger machine and will then give only apartial range of regulation for the smaller ma-chine.

) ., ,.. ) .-

TABLE 1

TABLE OF RESISTORS

FOR

CAM TYPE AUTOMATIC VOLTAGE REGULATORS FOR COMMERCIAL AND “M” TYPE

Figures below refer to approximate per cent of current change obtainable—(See Note at end of table)

Resistors

.

6ST01t Cam8r0iaL ~KS-3117

.0e6.ratorn 65-v6LtMar’pucamomt6r9cap. Condl-

Llat no. Ohm Amp. tlorl 1200 hp. 730 &p. SW Amp. 4CC Amp.200bmp.200Amp.10C Amp. M-M M-LO X-R H-7 M-d u+L/2 165 ~ ~

1 24 4 A 100u

2 10 “’? A lW lm 10Y lm 1~ 100

B 504

3 6.5 Q A 100

B ?eAO 73-W ?5-s0 ?s-90 7335-

4 4.5 10 A 100B So.?o eo-70 w-w SO.70 50-70 SC-70

s 3.2 15 A 100 103 100 100*B

~co* ~~.

60-70. EO-90 40.-s0 40-W

6 2.5 15 _A 100 100 100B 00-93 m-w BO-90 7oao

7 1.0 20 AB

lW 1006s”?3 6S7S 6S-’75 so-w Ssbvo

e 1.2,20 AB m-so so-w 704C 70%0

PRed

-117List no.

2

Item S&volt C-sold m COaarator,cap. Condl-

S3-vdt Wrypa 0en=at6rs

IluM .-p. tifm 1S3C mQ. low &p. Roo Mp. 6m AEp. 4CC Amp. ~ 7s Amp. u15 22-Lo m U-7 M-d 21-s4/z WI M-4 U&3

10 7 AB

100*

6.5 9 AB

100

4.5 10 AB w-so

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SO-PC

2.5 15 AB

K@ 100 100m-90 m-m

1.6 20 A 2.WS 100* ~oo* ~@J*62-75

lW6S-75 ?&w 70-W 70-W

TABLE OF RESISTORS (Continued)

CAM TYPE AUTOMATIC VOLTAGE REGULATORS FOR COMMERCIAL AND “ M “ TYPE GENERATORS

Figures below refer to approximate per cent of current change obtainabl~(See Note at end of table)

Lma-l a~o~ 33.701t Cammrcitd me Generators X5-voleTyp9

rs”-!!l17 cap. COndl-rlenorstors

List 60. ohms Amp. tion lSM Amp. lCOO Amp. em Amp. 600 Amp. 400 Amp. SC@ hp. 75 hp. U-15 W1O w M-7 U-6 lu-1/2 w M-4 u-s

e 1.2 20 A 100 100 100 100B so-so so-so so-w SO-70 W-70

9 . 5s ?0 A 160B 60-70 60-?0

100 MO60.70 60.70

10 .4s 35 A 100B lm ioo Loo

11 .4 45 A 106B 100 woo Oo-1oo OO-1OQ

NOTES: Per cent of current change = change in generator current output obtainable with resistor divided by generator current rating while maintaining propervoltage.

Condition A = Regulator gives regulation indicated as well as compensates for maximum lead drop between generator and points to which regulatoris connected under busy-hour load for central office and compensates for changes in generator from room to maximum operating tem-perature.

Condition B = Regulator will give regulation indicated only for constant or operating temperature of generator and compensates only for lead dropduring light loads for central otlice.

*Resistance per step higher than normal and should be used only for emergency operation.

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