e. The VFD shall feature soft start, linear acceleration, and coast to stop capabilities.
f. Base motor frequency shall permit motor to be utilized at nameplate voltage. Adjustable frequency range shall permit capacity control down to 15%.
g. The VFD shall have 150% instantaneous torque generation.
7. VFD Electrical Service (single point power):
a. The VFD shall have input circuit breaker with minimum 65,000 amp interrupt capacity.
b. The VFD shall have standard branch oil pump circuit breaker to provide power for chiller oil pump.
c. The VFD shall have standard 3 KVA control power transformer with circuit breaker to provide power for oil heater, VFD controls and chiller controls.
d. The branch oil pump circuit breaker and control power transformer shall be factory-wired.
e. Input power shall be 380/460 vac, ±10%, 3 Phase, 50/60 Hz, ±2% Hz.
8. Discrete Outputs:
115-v discrete contact outputs shall be provided for:
a. Circuit breaker shunt trip
b. Chilled water pump
c. Condenser water pump
d. Alarm status
9. Analog Output:
An analog (4 to 20 mA) output for head pressure reference shall be provided. This signal shall be suitable to control a 2-way or 3-way water regulating valve in the condenser piping.
10. Protection (the following shall be supplied):
b. Over voltage
c. Phase loss
d. Phase reversal
e. Ground fault
f. Phase unbalance protection
g. Single cycle voltage loss protection
h. Programmable auto re-start after loss of power
i. Motor overload protection (NEMA Class 10)
j. Motor over temperature protection
11. VFD Testing:
The VFD shall be factory-mounted, factory-wired and factory-tested on the chiller prior to shipment.
E. Evaporator and Condenser:
1. Evaporator and condenser shall be of shell and tube type construction, each in separate shells. Units shall be fabricated with high-performance tubing, steel shell and tube sheets with fabricated steel waterboxes. Waterboxes shall be nozzle-in-head type with stub out nozzles having Victaulic grooves to allow for use of Victaulic couplings.
2. Tubing shall be copper, high-efficiency type, with integral internal and external enhancement unless otherwise noted. Tubes shall be nominal 3/4-in. OD with nominal wall thickness of 0.025 in. measured at the root of the fin unless otherwise noted. Tubes shall be rolled into tube sheets and shall be individually replaceable. Tube sheet holes shall be double grooved for joint structural integrity. Intermediate support sheet spacing shall not exceed 36 in. (914 mm).
3. Waterboxes and nozzle connections shall be designed for 150 psig (1034 kPa) minimum working pressure unless otherwise noted. Nozzles should have grooves to allow use of Victaulic couplings.
4. The tube sheets of the cooler and condenser shall be bolted together to allow for field disassembly and reassembly.