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ECET 211 Electric Machines & Controls
Lecture 9-2
Adjustable-Speed Drives and PLC Installations (2 of 2)
Text Book: Electric Motors and Control Systems, by Frank D. Petruzella,
published by McGraw Hill, 2015
Paul I-Hai Lin, Professor of Electrical and Computer Engineering
Technology
P.E. States of Indiana & California
Dept. of Computer, Electrical and Information Technology
Purdue University Fort Wayne Campus
Prof. Paul Lin
Lecture 9-2 Adjustable-Speed Drives and PLC
Installations (2 of 2) A Quick Overview of Motor
Control Electronics (Chapter
9)
• Diodes, Transistors, Thyristors
and ICs
Part 1. AC Motor Drive
Fundamentals
• Variable-Frequency Drives (VFD)
• Volts per Hertz Drive
• Flux Vector Drive
Part 2. VFD Installation and
Programming
• Parameters
• Selecting the Drive
• Lines and Load Reactors
• Location
• Enclosures
Prof. Paul Lin 2
• Mounting Techniques
• Operator Interface
• Electromagnetic Interference
• Grounding
• Bypass Contactor
• Disconnecting Means
• Motor Protection
• Braking
• Ramping
• Control Inputs and Outputs
• Motor Nameplate Data
• Derating
• Types of Variable-Frequency
Drives
• PID control
• Parameter Programming
• Diagnostics and Troubleshooting
2
Lecture 9-2 Adjustable-Speed Drives and PLC
Installations Part 3. DC Motor Drive
Fundamentals (SKIP)
• Applications
• DC Drives – Principles of
Operation
• Single-Phase Input – DC Drive
• Three-Phase Input – DC Drive
• Field Voltage Control
• Non-regenerative and
Regenerative DC Drives
• Parameter Programming
Prof. Paul Lin 3
Part 4. Programmable Logic
Controllers (PLCs)
• PLC Sections and
Configurations
• Ladder Logic Programming
• Programming Timers
• Programming Counters
Lecture 9-2 Adjustable-Speed Drives and PLC
Installations VFD Installation and Programming Parameters
Selecting the Drive - Based on load categories of the driven
machinery
• Constant Torque – friction loads such as “Traction drive”
and Conveyors
• Variable-Torque – loads require much lower torque at low
speed, such as “Centrifugal fan, Pumps, and Blowers”
• Shock (impact) – loads pattern: normal load conditions
followed by a sudden, large load, such as engaging a
clutch that applies a large load
Prof. Paul Lin 4
3
Lecture 9-2 Adjustable-Speed Drives and PLC
Installations VFD Installation and
Programming Parameters
Line and Load Reactors
• Line Reactor – connect
between the Line and the
VFD controller
• Load Reactor – connect
between the VFD and the
motor
• Functions
Stabilize the current
waveform on the input
side of a VFD
Reduce harmonic
distortion and the burden
on the upstream electrical
equipment.
Prof. Paul Lin 5
Figure 10-16 VFD reactor
Lecture 9-2 Adjustable-Speed Drives and PLC
Installations VFD Installation and Programming Parameters
Location
• Mount the VFD drive near the motor.
• Enclosure surrounding the drive should be well ventilated
or in a climate-controlled environment.
• Avoid dusty, wet, corrosive environment, constant
vibration, direct sunlight
• Adequate lighting and sufficient working space: NEC
Article 110 lists requirements for working space and
illumination
Prof. Paul Lin 6
4
Lecture 9-2 Adjustable-Speed Drives and PLC
Installations VFD Installation and Programming
Parameters
Enclosures
• Select proper NEMA-type enclosure
• Figure 10-17 VFD mounted within an
enclosure
Mounting Techniques
• Din-rail mounting
• Through-hole mounting
• Air-flow, cooling fan
• Figure 10-18 VFD mounting technique
Prof. Paul Lin 7
Lecture 9-2 Adjustable-Speed Drives and PLC
Installations VFD Installation and Programming
Parameters
Operator Interfaces
• Figure 10-19 Typical VFD operator
interface
• VFD data accessible in real-time
Frequency output
Voltage output
Current output
Motor RPM
Motor kilowatts
DC bus volts
Parameter settings
Faults
Prof. Paul Lin 8
5
Lecture 9-2 Adjustable-Speed Drives and PLC
Installations VFD Installation and Programming
Parameters
Electromagnetic Interferences (EMI)
• Noise suppression procedure
Use a shielded power cable
EMI filter
Twisted control wiring leads
Maintain at least 8-inch
separation between control and
power wires
Prof. Paul Lin 9
Lecture 9-2 Adjustable-Speed Drives and PLC
Installations VFD Installation and Programming Parameters
Grounding
• All electric motor drives, motors, and related equipment must meet
the grounding and bonding requirements of NEC Article 250
• Figure 10-21 General grounding requirements for a VFD
Prof. Paul Lin 10
6
Lecture 9-2 Adjustable-Speed Drives and PLC
Installations VFD Installation and Programming Parameters
Bypass Contactor
• Intended for use in case of a drive failure for-time emergency service
• In HVAC application, this allows heating or cooling to be maintained at
all times
• Figure 10-22 Power circuit connection of a VFD bypass contactor
Prof. Paul Lin 11
Lecture 9-2 Adjustable-Speed Drives and PLC
Installations VFD Installation and
Programming Parameters
Disconnecting Means
• OSHA regulations
• NEC Article 430.102
Motor Protection
• VFD – short circuit
protection (fuses)
• VFD incorporated
protective functions
Stall prevention
Current limitation and
overcurrent protection
Short-circuit protection Prof. Paul Lin 12
Motor Protection (continue)
• VFD incorporated protective
functions
Undervoltage and
overvoltage protection
Ground fault protection
Power supply phase failure
protection
Motor thermal protection
through sensing of the motor
winding temperature
7
Lecture 9-2 Adjustable-Speed Drives and PLC
Installations VFD Installation and
Programming Parameters
Figure 10-23 Typical VFD
package
Prof. Paul Lin 13
Lecture 9-2 Adjustable-Speed Drives and PLC
Installations VFD Installation and Programming
Parameters
Braking
• Dynamic braking
• Regenerative braking
• DC-injection braking
Figure 10-24 Dynamic braking
applied to a VFD
Prof. Paul Lin 14
8
Lecture 9-2 Adjustable-Speed Drives and PLC
Installations VFD Installation and Programming
Parameters
Ramping
• The ability of a VFD to
increase or decrease the
voltage and frequency to an
AC motor gradually.
• Figure 10-25 Variable-
frequency ramping functions
Prof. Paul Lin 15
Lecture 9-2 Adjustable-Speed Drives and PLC
Installations VFD Installation and
Programming
Parameters
Control Inputs and
Outputs
Figure 10-26 Typical
VFD control inputs and
outputs
Prof. Paul Lin 16
9
Lecture 9-2 Adjustable-Speed Drives and PLC
Installations VFD Installation and
Programming Parameters
Control Inputs and Outputs
Figure 10-27 Input digital
connections for two-wire or
three-wire control with stop,
forward, reverse, and jogging
functions
Digital/relay outputs
Analog inputs – 0 to 10V DC or 4
to 20 mA signal
Analog outputs
Prof. Paul Lin 17
Lecture 9-2 Adjustable-Speed Drives and PLC
Installations VFD Installation and Programming Parameters
Motor Nameplate Data
Motor specifications are programmed into the VFD to ensure
optimum device performance as well as adequate fault and overload
protection
Figure 10-28 Entering motor nameplate data
Prof. Paul Lin 18
10
Lecture 9-2 Adjustable-Speed Drives and PLC
Installations VFD Installation and Programming
Parameters
Two earlier types of Variable-Frequency
Drives
Figure 10-29 Simplified circuit of a
voltage source inverter (VSI)
• Also called “variable voltage
inverter”
Figure 10-30 Simplified circuit of a
current-source inverter (CSI)
• For large drives (about 200 hp)
Prof. Paul Lin 19
Lecture 9-2 Adjustable-Speed Drives and PLC
Installations VFD Installation and Programming
Parameters
PID Control (Built-in)
Figure 10-31 PID loop
Prof. Paul Lin 20
11
Lecture 9-2 Adjustable-Speed Drives and PLC
Installations VFD Installation and
Programming Parameters
Parameter Programming
Parameter – a variable
associated with the operation
of the drive that can be
programmed or adjusted
Common adjustable
parameters
• Preset speeds
• Min and max speeds
• Acceleration and
deceleration rates
• Two- and three-wire remote
control modes
Prof. Paul Lin 21
Common adjustable parameters
• Stop modes: ramp, coast, DC
injection
• Automatic torque boost
• Current limit
• Configurable input jog
• V/Hz settings
• Carrier frequency
• Programmed password
Lecture 9-2 Adjustable-Speed Drives and PLC
Installations
Prof. Paul Lin 22
Part 4. Programmable Logic Controllers (PLCs)
• PLC Sections and Configurations
Figure 10-50 The major sections of a PLC system
12
Lecture 9-2 Adjustable-Speed Drives and PLC
Installations
Prof. Paul Lin 23
Part 4. Programmable Logic Controllers (PLCs)
PLC Sections and Configurations
• Figure 10-51 Fixed programmable controller (Micro PLC)
Lecture 9-2 Adjustable-Speed Drives and PLC
Installations
Prof. Paul Lin 24
Part 4. Programmable Logic Controllers (PLCs)
PLC Sections and Configurations
• Figure 10-52 Modular programmable controller
13
Lecture 9-2 Adjustable-Speed Drives and PLC
Installations
Prof. Paul Lin 25
Part 4. Programmable Logic
Controllers (PLCs)
Ladder Logic Programming
• Figure 10-53 PLC relay ladder
logic program
• Figure 10-54 Hard-wired
start/stop circuit
Lecture 9-2 Adjustable-Speed Drives and PLC
Installations
Prof. Paul Lin 26
Part 4. Programmable Logic Controllers (PLCs)
Ladder Logic Programming
• Figure 10-55 Basic PLC instructions
14
Lecture 9-2 Adjustable-Speed Drives and PLC
Installations
Prof. Paul Lin 27
Part 4. Programmable Logic Controllers (PLCs)
Ladder Logic Programming
• Figure 10-56 Programmed start/stop circuit
Lecture 9-2 Adjustable-Speed Drives and PLC
Installations
Prof. Paul Lin 28
Part 4. Programmable Logic
Controllers (PLCs)
Ladder Logic Programming
• Figure 10-57 PLC wiring
designed to implement the
motor start/stop control
15
Lecture 9-2 Adjustable-Speed Drives and PLC
Installations
Prof. Paul Lin 29
Part 4. Programmable Logic Controllers (PLCs)
Ladder Logic Programming
• Figure 10-58 Programmed start/stop circuit with remote
standby and run pilot lights
Lecture 9-2 Adjustable-Speed Drives and PLC
Installations
Prof. Paul Lin 30
Part 4. Programmable Logic
Controllers (PLCs)
Ladder Logic Programming
• Figure 10-59 Wiring changes
for remote pilot lights
16
Lecture 9-2 Adjustable-Speed Drives and PLC
Installations
Prof. Paul Lin 31
Part 4. Programmable Logic
Controllers (PLCs)
Programming Timers
Figure 10-60 On-delay timer
instruction
• On-delay timer (TON)
• Off-delay timer (TOF)
• Retentive timer (RTO)
Lecture 9-2 Adjustable-Speed Drives and PLC
Installations
Prof. Paul Lin 32
Part 4. Programmable
Logic Controllers (PLCs)
Programming Timers
Figure 10-61 On-delay
programmed timer
• Type of timer: TON
• Timer number:
Address T4:0
• Time base: 1.0 sec
• Present time: 15; ( 1
sec x 15 = 15 sec)
• (EN): Enable bit
• (DN): Done bit
17
Lecture 9-2 Adjustable-Speed Drives and PLC
Installations
Prof. Paul Lin 33
Part 4. Programmable Logic Controllers (PLCs)
Programming Counters
• Figure 10-62 Wiring for the on-delay timer using the Allen-
Bradley SLC 500 modular controller
• Address I: 1/2 – Input: slot 1/terminal 2
• Address O:2/3
• Address O:2/8
Lecture 9-2 Adjustable-Speed Drives and PLC
Installations
Prof. Paul Lin 34
Part 4. Programmable Logic
Controllers (PLCs)
Programming Counters
• Figure 10-63 Up-counter
(CTU) instruction
• Type of counter: Up-counter
(CTU)
• Counter number: Address
C5: 1
• Preset value: 7
• Accumulated value: Initially
set at 0
• (CU): enable bit
• (OV): Overflow bit
• (RES): Reset
18
Lecture 9-2 Adjustable-Speed Drives and PLC
Installations
Prof. Paul Lin 35
Part 4. Programmable Logic Controllers (PLCs)
Programming Counters
• Figure 10-64 Programmed up-counter
Lecture 9-2 Adjustable-Speed Drives and PLC
Installations
Prof. Paul Lin 36
Part 4. Programmable Logic Controllers (PLCs)
Programming Counters
• Figure 10-65 Wiring for the up-counter implemented using the
Allen-Bradley SLC 500 controller
19
Lecture 9-2 Adjustable-Speed Drives and PLC
Installations
Prof. Paul Lin 37
Part 4. Programmable Logic Controllers (PLCs)
Programming Counters
• Figure 10-66 Parking garage counter
Summary & Conclusion
Questions? Contact Prof. Lin through:
Email: [email protected]
LINE Group Discussion Forum
Prof. Paul Lin 38