Specifications

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d. Adjustable pressure ramp-up and ramp-down to assure surge free pressure
regulation.
e. After a drop in pressure, gradually increase system pressure over a user adjustable
period of time to eliminate surging.
f. Rate of change of pressure control to anticipate and eliminate rapid pressure
changes caused by changing system demand.
Discharge pressure regulation shall be by a Variable Frequency Drive. Adjustment of regulated downstream
pressure shall be accomplished though the control panel operator interface. Hydraulic type, pilot controlled
pressure reducing valves shall not be accepted.
5.2 VARIABLE FREQUENCY DRIVE (VFD)
The variable frequency drive shall be IGBT based with selectable carrier frequency up to 15 KHZ. The VFD
shall include terminals for incoming power, motor output power and control terminals.
The VFD shall generate a sine-coded, variable voltage/ frequency, three phase output for optimum speed
control. The VFD shall incorporate power loss ride-through for a minimum of 2 seconds. VFD protective
features shall include current limit, auto restart, short circuit protection, electronic motor overload protection
and ground fault protection. The VFD shall have a push button programming display for easy access to
operation parameters. The VFD shall be protected on the primary side by fuses of the appropriate amperage.
Overload capacity: 120% rated output current for one minute. Voltage Fluctuation: +10%, -15%. Sine wave
PWM with full range, automatic torque boost. Frequency Control Range: 0.1 to 400Hz. Frequency Accuracy:
Digital, 0.01Hz, Analog. .1%. Motor overload protection, Instantaneous Over current of 180% of rated output
current. Over voltage at 820VDC if 460V input. Under voltage: user adjustable. Momentary Power Loss: up to
2 second ride through. Electronic Ground Fault. LED capacitor charge indicator. Input Phase loss alarm.
Ambient temperature range of + 14 to 104 degrees F. Humidity of 95% non-condensing.
5.3 MAIN SERVICE DISCONNECT
A three-pole, main service rated disconnect shall be contained within the NEMA 4 control enclosure. An
externally mounted service disconnect shall not be acceptable. Disconnect shall isolate all power to the control
enclosure. The disconnect shall have an operating handle mounted in the enclosure door, mechanically
interlocked to prevent entry while disconnect is in the ON position.
5.4 MOTOR FUSES, STARTERS AND OVERLOADS
Each started shall be protected on each leg by a time delay fuse of the appropriate amperage. Motor starter
coils shall be 120 volt operated. Overload relays shall be electronic type, ambient compensating and
differential tripping type. Bi-metallic or melting alloy type overloads shall not be permitted. The overload shall
protect each power leg and shall be set to the motor's full-load current rating. Further protection shall include
sensitivity to current imbalance and single phase conditions.
5.5 CONTROL TRANSFORMER
A control transformer shall provide 120 volt power to the pump station controls. The control transformer shall
be protected on the primary and secondary sides with appropriately sized fuses. No load other than the pump
station controls shall be supplied by the control transformer.
5.6 CONTROL LOGIC
The pump sequence controller shall be an industrial grade PLC with diagnostic LED's for monitoring of
discrete inputs and outputs. Not less than two additional analog inputs and outputs shall be standard for