“PEAK PLUS”
GENERATOR-UTILITY INTERCONNECT
CONTROL SYSTEM
ENGINEERING BRIEF
EB015 Rev 0 95/07/01
“PEAK PLUS” CONTROL SYSTEM
DESCRIPTION OF SYSTEM
The “Peak Plus” system is designed to allow the generator set to be paralleled with the utility
supply for Peak Shaving and/or testing operations. Sophisticated electronic controls ensure
that the two sources, phases and voltage are matched prior to synchronizing. Additional
circuitry provides for extensive automatically and manually initiated modes of operation, as well
as ensuring adequate protection of the utility’s system during periods of interconnection.
The “Peak Plus” system is comprised of the following components:
• Electrically operated drawout, 100% rated air circuit breakers
• Protective relays
• Utility/Generator instrumentation
• Automatic synchronizer
• Engine governor controller loadsharing module
• VAR/Powerfactor control
• Peak Plus 500 transfer controller
Existing local generator set controls utilized in conjunction with Peak Plus system are:
- Auto start/stop controller
- Engine electronic governor controller
- Generator automatic voltage regulator
SEQUENCE OF OPERATION
The synchronizing system will have two basic modes of operation, one completely automatic
and the second manually operated. The two position selector switch (25CS) will initiate
operation as follows:
Auto
The generator automatically synchronizes to the utility supply and closes the
generator/utility tie circuit breaker.
Manual
The synchroscope, sync lights and manual sync check relay are enabled (automatic
synchronizing is inhibited).
System Paralleling transfer operation will be controlled by separate selector switches.
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“PEAK PLUS” CONTROL SYSTEM
43CS PEAK SHAVE OPERATION SWITCH
AUTO
The generator set will automatically start and synchronize to the utility supply when a
remote signal is issued by the building management system. The generator’s load level
may be manually or automatically set as selected by the loading control switch. When
the remote signal is opened, the generator will ramp it’s load down, trip off line,
cooldown, then stop.
OFF
Peak shave operation is disabled. Note: The generator set will still automatically start
upon a utility power failure provided the load control panel is set for automatic operation.
MAN
The generator set will start/stop as controlled by pushbuttons located on the front of the
panel. Synchronizing and loading may be automatic or manual subject to other switch
positions.
43LC LOAD CONTROL SWITCH
AUTO
The generator set will automatically assume a load level as determined by the
automatic loading controller. The generator load level set point is adjustably set from a
panel mounted rheostat.
MAN
The generator’s load level is set manually via panel mounted potentiometer “Generator
manual load adjust”.
GLA - GENERATOR LOAD ADJUST POTENTIOMETER
The generator’s load may be manually set via potentiometer provided the load control switch
(43LC) is in the manual position.
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“PEAK PLUS” CONTROL SYSTEM
COMPONENT DESCRIPTION
SWITCHBOARD
Single vertical section to be free standing, dead front, cubicle size as indicated,
completely metal enclosed, self supporting structure, 90” high. Breaker will be located
in the lower compartment.
Barriered metering and control sections will have a metal backboard. The control
section shall incorporate metering, switching, protective relaying and control devices.
Ventilation openings will be provided where required.
The switchboard will be provided with lifting hooks and built-in angles or channels to
facilitate bolting to the floor. Exterior and interior steel surfaces will be properly cleaned
and finished with enamel paint - color ASA 61 grey. Backboards will be painted white.
The bussing, where necessary, will be tin-plated copper of sufficient size to limit
temperature rise to 65°C and rated to withstand available fault current during short
circuit condition. Switchboard will bear CSA label C31.
UTILITY INTERCONNECT BREAKER
Breaker will be drawout air circuit style minimum 42KA rms symmetrical at 600 Volt with
100% continuous rating. Three drawout positions - Test, Disconnect and Withdrawn will
be provided. Breaker will have 120VAC electrical operation with 24VDC shunt trip and
120VAC close coils.
Breaker will have microprocessor based integral current sensor with long time, short
time, and instantaneous trip functions. Breaker control switch (52CS) will be supplied to
provide manual trip control at any time, and closing control provided the permissive
sync logic is satisfied.
AC INSTRUMENTATION
Analog indicating type, 4-1/2, 1% accuracy, flush panel mounting
Generator
• Voltmeter, Ammeter, Frequency Meter, Powerfactor, Kilowatt
• Voltmeter and Ammeter four position control selector switches
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“PEAK PLUS” CONTROL SYSTEM
Utility
• Voltmeter, Frequency Meter, Kilowatt , Powerfactor
• Voltmeter four position control selector switch
PROTECTIVE RELAYING
A Utility grade protection system will be provided. The relays will be flush mounted on
the utility cabinet door. The protective relays are permitted to function only when the
generator set is closed to the bus. Relays provided will be Basler BE-1 series as
follows:
• BE1-32U
- Utility reverse power
• BE1-27/47/59
- Negative Sequence/Under/Overvoltage
• BE1-81O/U - Under/Over Frequency
• BE1-25
- Sync Check
A Generator reverse power relay will be separately provided to protect the generator
from reverse power should the engine lose power while in the parallel generation mode.
This industrial grade relay will be internally mounted and annunciated with the PP-500
controller.
SYNCHRONIZING/INTERCONNECT CONTROL
Auto Synchronizer (25)
This unit automatically monitors and controls the generator speed (frequency) to match
the phase relationship between the generator set and utility service during uninterrupted
system paralleling. The synchronizer provided will be a Woodward type SPMA.
VAR/Powerfactor Module
This unit controls the Kilovar load (i.e. Powerfactor) of the generator when in the parallel
generation mode in conjunction with the generator voltage regulator.
The VAR/PF controller provided will be a Basler model SCP-250.
Sync Check Relay (25A)
This relay provides backup protection to the automatic synchronizer. When
synchronizing, both ASU and 25A relays must initiate a breaker close signal prior to a
breaker closure.
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“PEAK PLUS” CONTROL SYSTEM
Generator Load Sensor
The generator load sensor control provides the load sharing capability for the engine
governor controller Woodward model 2301A. The load sensor provided will be a
Woodward type 2500.
Synchroscope
Allows monitoring of phase relationship between the normal and generator supply
during uninterruptable transfer operation.
Programmable Logic Controller
The programmable logic controller (PLC) monitors and controls the utility
interconnect synchronizing operation. System operating mode is based on inputs
from the control switches 25CS, 43CS and 43LC.
The PLC monitors the status condition of the breakers, associated protective relays
and transfer switch(es) in the system and provides interconnect breaker operation
commands based on the inputs monitored.
The PLC will control the generator Kilowatt soft loading and unloading when
connected bus in parallel with the utility. The bumpless power transfer will be
controlled to near zero power level during periods before and after closing and
opening of the interconnect breaker.
PP 500 Controller
The PP 500 controller is used in conjunction with the PLC to provide an operator
interface for the Utility Interconnect Control Scheme. A mimic bus showing the
operator and transfer switch status is provided. Separate indicator lamps provide
visual indication for the following functions:
Operating Mode
• Synchronizing
- Green
• Parallel with Utility
- Green
System Alarm
• Generator Reverse Power
- Red
• Utility Fail in Parallel Mode
- Red
• Fail to Synchronize
- Red
• Control Power Available
- Green
Lamp test and fault reset push buttons are provided.
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