Reliance Electric
VTAC 7 Specifications
1-400 HP @ 460 Volts
1-100 HP @ 208 Volts
VARIABLE FREQUENCY DRIVES
This specification should be used to detail the requirements for a 1 through
400 HP at 460 Volts and 1 through 100 HP at 208 Volt AC Variable Frequency
Drive (VFD).
1.0 GENERAL
A single manufacturer of both motors and drives shall provide, coordinate, and start-up a
drive package to ensure both proper application of the motor to the control and of the drive
package to the driven load. The Variable Frequency Drive shall be manufactured by
Reliance Electric Company.
A. The standard Variable Frequency Drive (VFD) and all the optional modifications shall
mount within a packaged NEMA 1 or NEMA 12 (1-60 HP @ 460 Volts, 1-25 HP @ 208
Volts) enclosure.
B. Motor and VFD shall be of the same manufacturer.
C. VFD shall be current rated at 8 kHz carrier frequency for VFD's 1-150 HP and 4 kHz
for VFD's 200-400 HP. In cases where motor audible noise is not critical to the driven
equipment, 4 kHz may be used in drives above 60 HP. All HP ratings shall meet or exceed
Table 430-150 of the NEC, 3 Phase Motor Full Load Currents. HP, Maximum Current, and
Rated Voltage shall appear on the drive nameplate.
D. VFD shall not generate damaging transistor pulses at lead lengths up to 500 feet greater
than limits set by NEMA MG1 section 31.40.4.2. Minimum rise time at 500 feet shall be .1
microseconds and peak voltage shall remain under 1600 volts per this standard. Motors
shall also be designed to withstand this rise time and peak voltage level.
1.1 BASIC DESCRIPTION
The VFD shall be a fully digital PWM using very large scale integration (VLSI) techniques
as well as surface-mount technology for increased reliability. The VFD shall use two 32-bit
microprocessors with 12-bit resolution to allow stepless motor control from 0.1% to 110%
of motor base speed.
All programmable settings shall be held in non-volatile memory and shall not be affected
by power outages, brownouts, power dips, etc. The VFD shall have initial programmable
settings intact from the factory without the need of battery backup. the VFD shall not need
to be programmed at the job site prior to being able to run a motor, but shall be ready to
run a motor as soon as power connections are made.
Programming at the job site to accommodate specific local applications requirements, such
as frequency avoidance and preset speeds shall be available to the user.
VFD multiple motor operation at the same frequency and speed shall be possible as long as
the sum of the connected motor full load sine wave currents are less than or equal to 90%
of the VFD maximum continuous current rating. Supply and Return Fan horsepower
requirements are as stated in schedule documents. All high voltage components within the
enclosure shall be isolated with steel or polycarbonate covers.
1.2 CODES/STANDARDS
VFD and options shall be c UL* 508 listed. NEMA 12 enclosed VFD shall be UL ä
approved for mounting in conditioned air ducts and plenums (UL™ 1995). The drive and
options shall comply with the applicable requirement of the latest standards of ANSI,
NEMA, National Electric Code NEC, NEPU-70, IEEE 519-1992, FCC Part 15 Subpart J,
CE 96. VFD manufacturer shall be ISO 9001 certified.
1.3 EXPERIENCE
The manufacturer of the VFD described in this specification shall have a minimum of 20
years experience in the design, construction and application of adjustable frequency
controls and motors.
1.4 QUALITY ASSURANCE
The VFD shall be subject to but not limited to the following quality assurance controls,
procedures and tests.
A. The VFD's shall be designed, manufactured, and tested in the United States of America.
Compliance with this specification shall be stated in writing at time of bid. A minimum 80
% US. content will be considered acceptable.
B. During the Design Engineering process for the VFD the following quality assurance
controls, procedures and tests shall be implemented.
1. Each new product design shall undergo a 4000 hour pre-production burn-in test. Up
to ten units may be used to accumulate this entire time. Each unit shall be
temperature cycled between 0 and 50ºC during this time period.
2. Digital integrated circuits shall undergo functional and reliability tests. Regulator
circuits must use reliable and compact surface mount construction. These circuits
shall be 100% tested on computer controlled systems. Test equipment must be
documented, controlled and calibrated to ISO 9001 standards.
3. Each drive power circuit shall be tested under motor load conditions. While loaded,
the output waveform shall be monitored for correct PWM algorithm. Short circuit
testing shall be done to UL standards and an AIC rating placed on each controller
nameplate.
4. All components utilized with the basic VFD like contactors, overload relays,
pushbuttons, pilot devices, and other control devices shall be UL. recognized. These
components shall be manufactured by Allen Bradley Company.
C. After initial product quality assurance testing, each drive shall be subjected to the
following quality control procedures.
1. Every VFD shall be functionally tested under motor load. During this load test the
VFD shall be monitored for correct phase current, Phase voltages, and motor speed.
Correct Current Limit operation shall be verified by simulating a motor overload.
2. A HYPOT voltage test shall be performed using at least 2715 VDC. Leakage
currents during this test must not exceed 100 micro amps. This test insures proper
grounding procedures have been followed during manufacturing.
3. Verification of proper factory presets by scrolling through all parameters shall be
performed to ensure proper microprocessor settings. The computer port should also
verify that the proper factory settings are loaded correctly in the drive.
4. All options shall be functionally tested including operation of a motor in the Bypass
mode if supplied. Proper heater coil installation in motor overload , if supplied, shall
be verified.
D. Quality control systems shall conform to the ISO9001 standard. Under this system,
quality assurance for design/development, production, installation and servicing of the
proposed manufactures equipment shall be certified ISO9001. Written certification of
conformance to this standard shall be supplied at time of bid.
1.5 SERVICE
A. The VFD manufacturer shall maintain and staff world-wide service centers. The
manufacturers shall have the ability to test both the controller and the motor in these
service centers.
1. Start-up shall be included for each VFD provided.
2. The service engineers shall be employed by the manufacturer or be certified by the
manufacturer and provide start-up service including physical inspection of drive and
connected wiring and final adjustments to meet specified performance requirements.
B. Training shall be available on site by employees of the manufacturer and shall be in
addition to the start-up serviced. Training shall include system concepts and basic
troubleshooting.
C. A reasonable supply of spare parts must be kept available for the VFD to meet ordinary
repair requirements for the immediate future. In addition, spare parts shall be available
within 24 hours of notification through a local Service Center, by the user.
2.0 VARIABLE FREQUENCY DRIVE
The VFD manufacturer shall provide, at minimum the basic features, adjustments, general
options and modifications as specified below.
2.1 BASIC FEATURES
The VFD shall have the following basic features:
A. All 1-150 HP 460 Volt VFD's current ratings shall be at 8 kHz carrier frequency. No
derating of the drive shall be required due to increasing this switching frequency for motor
noise reduction An alternate 4 kHz 75-200 HP 460 Volt Wall Mounted Drive may be
supplied where motor audible noise is not critical to the installation. VFD's from 200-400
HP 460 Volt shall maintain current ratings at 4 kHz. VFD's from 1-100 HP 208 Volt shall
be rated at 8 kHz carrier frequency. Drives that automatically reduce the carrier frequency
as load is increased shall not be supplied. Operator controls shall be mounted on the door
of the cabinet and consist of a membrane command center which allows manual stop/start,
speed control, local/remote status indication, manual or automatic speed control selection,
and run/jog selection. In addition, the command center will serve as a means to configure
controller parameters such as Min Speed, Max Speed, Acceleration and Deceleration
times, Volts/Hz ratio, Torque Boost, Slip Compensation, Overfrequency Limit, and
Current Limit. Potentiometers will not be allowed for these settings. The controller shall
have an internal means of deactivating keypad parameter adjustments to eliminate
unauthorized data entry.
B. A slip compensation circuit for accurate 1% speed regulation without the need of a
tachometer.
C. Adjustable DC braking that is programmable from the command center settable in both
amplitude and duration.
D. An electronic overload circuit designed to protect an AC motor operated by the VFD
output from extended overload operation on an inverse time basis. This Electronic
overload shall be ULä and NEC recognized as adequate motor protection. No additional
hardware such as motor overload relays or motor thermostats shall be required. E.
Automatic and manual torque boosts that are settable within the control to accelerate high
inertia fan and pump loads. F. An LED display mounted on the door of the cabinet that
digitally indicates:
1.
2.
3.
4.
5.
6.
7.
8.
Frequency output
Voltage output
Current output
Motor RPM
Input kW
Elapsed Time
Time Stamped Fault Indication
DC Bus Volts
G. The capability of starting into a rotating load regardless of direction without the need of
a time delay upon a start command.
H. Relay contacts for remote indication of drive fault or motor running for inter-wiring to
other user supplied devices.
I. An automatic restart circuit which is settable by number of restart attempts and time
interval between restarts.
J. Three critical frequency avoidance bands, which can be programmed in the field, enable
the controller to avoid resonate frequencies of the driven equipment. Each critical
frequency avoidance band shall have a bandwidth adjustable via keypad entry of up to 10
Hz.
K. Eight programmable preset speeds which will force the VFD to a preset speed upon a
user contact closure. This feature shall be set digitally by entering data via the door
mounted membrane command center. These shall be utilized for user specified purge
functions.
L. The VFD shall have the capability of riding though power dips up to 10 seconds without
a controller trip depending on load and operating condition. In this extended ride through,
the drive shall use the energy generated by the rotating fan as a power source for all
electronic circuits.
M. Multiple Volts/Hz patterns settable in one Hz increments.
N. Jog speed selection.
O. RS232 Port for Configuration, Control, and Monitoring.
P. An isolated electrical follower capability shall enable the Adjustable Frequency
Controller to follow a 0-20mA, 4-20mA or 0-4, 0-8, 0-10 volt DC grounded or ungrounded
speed signal.
Q. A isolated 0-10 V or 4-20 ma output signals for computer controlled feedback signals
shall be selectable for speed or current.
R. For ultra-smooth acceleration and deceleration capabilities, the drive shall have a preprogrammed "S" curve ramp which can be activated locally.
S. Flux Vector PWM operation with "trip free" circuitry to eliminate nuisance faults.
T. IGBT transistors with a selectable carrier frequency between 4 and 8 kHz
2.2 PROTECTIVE CIRCUITS AND FEATURES
The VFD shall include the following protective circuits and features:
1. Motor current exceeds 200% of drive continuous current rating.
2. Output phase-to-phase short circuit condition.
3.
4.
5.
6.
7.
8.
Total ground fault under any operating condition.
High input line voltage.
Low input line voltage.
Low input line voltage.
Loss of input or output phase.
External fault. (This protective circuit shall permit wiring of remote N.C. safety
contact to shut down the drive). User supplied end switches, thermal switches, firestats, freeze-stats inputs will be connected to this VFD supplied circuit.
9. Metal oxide varistors for surge suppression shall be provided at the VFD input
terminals.
2.3 ADJUSTMENTS
The following adjustments shall be provided:
A. Maximum frequency (1 - 120Hz) with factory setting at 60Hz.
B. Minimum frequency (5 to 60Hz).
C. Acceleration (0.1 to 999.9 seconds).
D. Deceleration (0.1 to 999.9 seconds).
E. Volts/Hz ratio factory set for 460 Volts at 60Hz or 208 Volts at 60 Hz.
F. Current limit (50 to 110%) drive continuous rating.
2.4 SERVICE CONDITION
The VFD shall be designed and constructed to operate within the following service
conditions:
A. Suitable for continuous operation at an ambient temperature of 0ºC to 40ºC, elevation
up to 3300 feet altitude with a relative humidity to 95% non-condensing.
B. AC line variation of -10% to + 10% Voltage and +/-5 Hz Frequency.
C. AC line distribution system capacity shall not exceed 30,000 Amps symmetrical
available fault current.
2.5 GENERAL OPTIONS AND MODIFICATIONS
The following options shall be included as specified in the document:
1. The energy efficient motor manufacturer shall performance-match and guarantee full
nameplate horsepower and speed when operated on the specified VFD and also
2.
3.
4.
5.
6.
7.
provide as a minimum the mechanical design, electrical design and basic features as
follows:
All motors shall conform to the latest applicable requirements of NEMA, IEEE,
ANSI and NEC standards.
Motors shall be of an energy efficient design meeting NEMA efficiency table 12.10
or a premium efficient design.
Motors shall be designed for continuous duty operation, NEMA design B.
Open Drip Proof Motors and Totally Enclosed Motors to be furnished with Class F
insulation.
Motor Insulation System shall conform to all of the requirements of NEMA MG1
part 31 section 31.40.4.2 for peak voltage withstand capability.
Stainless steel nameplates with:
A. NEMA efficiency index nominal efficiency (MG1-12.53b) B. AFBMA bearing
numbers C. Lubrication instructions
B. Isolation Transformer in a NEMA 1 enclosure, for separate mounting, for use on threephase 60Hz input power of the voltage specified to provide three-phase, 60Hz output for
the Variable Frequency Drive.
C. Complete Contactor ByPass shall be provided to allow motor to be safely transferred
from VFD output to the AC line, or from the AC line to the VFD, while the motor is at
zero speed. The contactor ByPass shall utilize two motor contactors electrically
interlocked. One contactor is to open and close the connection between the VFD output
and the motor. The other contactor will open and close the connection between the ByPass
power line and the motor, providing "across the line" starting. Motor protection is to be
provided in the "ByPass" mode by a bi-metallic Class 20 Smart Motor Protection
adjustable overload relay. Relay control logic shall also be included within the VFD
enclosure to allow the same "START/STOP" command to operate the motor in either
mode. The relay logic shall be 115 Volts. The ByPass circuit shall include a second
disconnect installed in the VFD to provide the ability to safely troubleshoot and test the
controller , both energized and de-energized, while the motor is running in the "ByPass"
mode. A contact closure shall be provided to indicate that the drive is in the "ByPass"
mode. A Remote/Local selector switch shall also be provided to transfer control from the
keypad to user wired signals. Form "C" Normally Open and Normally Closed contacts
shall be provided for both Run and IET/Drive Stopped. The entire ByPass option shall be
packaged with the controller enclosure and be mechanically isolated from the VFD.
D. Input line fuses shall provide protection for the input rectification circuit using Class J
fuses with interrupting rating of 200,000 AIC. The series interrupting rating of the VFD
and fuses shall be a minimum of 30,000 AIC and shall be stated in the VFD Instruction
Manual as required by UL
E. A main input disconnect shall mount within the standard NEMA 1 or NEMA 12
enclosure for positive power disconnect of the VFD. It shall have the capability for door
padlocking.
F. A three phase 3% impedance Input Line Reactor shall be provided to minimize drive
harmonics on the AC line and protect the drive from damaging electrical system transients.
G. In units from 1-40 HP a door interlocked main input disconnect shall be provided. This
disconnect shall also increase the short circuit interrupting capacity from 30,000 to 85,000
amps symmetrical fault current. This high fault current option shall be UL listed and
suitable for use on distribution systems feeds up to 4,000 KVA with 5% minimum
impedance. To rate the drive at 85,000 AIC, a three phase Line Reactor must be provided
with the appropriate disconnect.
H. Provide harmonic measurements at the specified Point of Common Coupling (PCC) .
This study will provide the user with data on the actual power system waveforms.
Upstream transformers maximum load current shall be the unity factor for all data supplied
in percentages. Data shall include total harmonic voltage and current distortion as required
by IEEE 519-1992 standard. Additionally, individual current harmonic data shall be
included to the 13th harmonic.
I. I/O Expansion Interface Card with the following features:
1.
2.
3.
4.
5.
6.
7.
PI regulator for setpoint pressure control
Four Isolated 24 VDC programmable digital inputs
An additional analog input for speed feedback to PI regulator
One Frequency Input (0 to 200 Hz) for digital control of current limit
Four programmable Isolated Digital Outputs (24 VDC rated)
One Form A output relay rated at 250 VAC or 24 VDC
Two NO/NC programmable output relays rated at 250 VAC or 24 VDC Additional
control digital and analog signals can be activated through the standard keypad for
customized interface with specific Building Automation Systems.
J. Johnson Controls Metasys(tm) option card allows direct connection from the VTAC 7 to
the Johnson N2 bus architecture. All configuration and control functions can be accessed
through this card. Allows direct communication between the VTAC 7 microprocessor and
the host Johnson system. Fault diagnostics, start/stop, speed commands, and all drive
feedback's shall be available over a single RS485 communication connection. Discrete
signals such as ByPass Run or Interlock Open shall also be mapped through the drive
terminal strip to the Metasys system. The card shall have the ability to be used in a
"monitor only" mode where control shall be from a AHU or similar type controller directly
wired to the drive.
Reliance document VTAC-409
January 1998
Copyright 2002 Rockwell Automation
For more information call 216-2667000.