Variable Speed Drive - York YK Manual

FORM 160.75-EG1 (519)
Guide Specifications (Cont'd)
O. The capability to interface with a building automation system via hard-wired connec-
tions to each feature to provide:
1. Remote chiller start and stop
2. Remote leaving chiller liquid temperature adjust
3. Remote current limit setpoint adjust
4. Remote ready to start contacts
5. Safety shutdown contacts
6. Cycling shutdown contacts
7. Run contacts

VARIABLE SPEED DRIVE

A variable speed drive shall be factory-installed on the chiller. It shall vary the compressor
motor speed by controlling the frequency and voltage of the electrical power to the motor.
The adaptive capacity control logic shall automatically adjust motor speed and compres-
sor pre-rotation vane position independently for maximum part load efficiency by analyz-
ing information fed to it by sensors located throughout the chiller.
Drive shall be PWM type utilizing IGBTs with a displacement power factor of 0.95 or better
at all loads and speeds.
The variable speed drive shall be unit-mounted in a NEMA- 1 enclosure with all power
and control wiring between the drive and chiller factory-installed, including power to the
chiller oil pump. Field power wiring shall be a single-point connection and electrical lugs
for incoming copper power wiring are provided. The entire chiller package shall be certi-
fied to standard UL-1995 by a nationally recognized testing laboratory.
The variable speed drive is cooled by a closed loop, fresh water circuit consisting of a
water-to water heat exchanger and circulating pump. All interconnecting water piping is
factory installed and rated for 150 psig (10.3 barg) working pressure.
The following features shall be provided: a door interlocked circuit breaker, capable of
being padlocked; UL listed ground fault protection; overvoltage and under voltage protec-
tion; 3-phase sensing motor overcurrent protection; single phase protection; insensitive
to phase rotation; over temperature protection; digital readout at the chiller unit control
panel of:
• Output Frequency
• Output Voltage
• 3-phase output current
• Input Kilowatts (kW) and Kilowatt-hours (kWh)
• Self diagnostic service parameters
Separate meters for this information shall not be acceptable.
108 JOHNSON CONTROLS