York YMC2 - Motor; Variable-Speed Drive (VSD)

JOHNSON CONTROLS
FORM 160.84-EG1 (617)
64
Guide Specifications (Cont'd)
MOTOR
The compressor motor shall be a hermetic, oil free, permanent magnet type directly cou-
pled to the compressor. The motor will be bolted to a cast iron adapter plate mounted
on the compressor to provide factory alignment of the shaft. The motor shaft shall be
supported on active magnetic radial and thrust bearings. Magnetic bearing control shall
be equipped with auto vibration reduction and balancing systems. During a power failure
event, the magnetic bearings shall remain active throughout the compressor coast down.
Rolling element bearings shall be provided as a backup to the magnetic bearings de-
signed for emergency touch down situations. Motor stator and rotor shall be equipped with
a pressure driven refrigerant cooling loop to maintain acceptable operating temperatures.
VARIABLE-SPEED DRIVE (VSD)
A VSD shall be factory installed on the chiller. It will vary the compressor motor speed by
controlling the frequency and voltage of the electrical power to the motor. The capacity
control logic shall automatically adjust motor speed for maximum part-load efficiency by
analyzing information fed to it by sensors located throughout the chiller.
Drive shall be PWM type utilizing IGBT’s with a displacement power factor of 0.97 or bet-
ter at all loads and speeds.
The VSD shall be unit mounted in a NEMA -1 enclosure with all power and control wiring
between the drive and chiller factory installed. Field power wiring shall be a single point
connection and electrical lugs for incoming power wiring will be provided. The entire chiller
package shall be UL listed.
The VSD shall be cooled using condenser water and all cooling connections shall be fac-
tory installed.
The following features will be provided:
• Door interlocked rotary disconnect switch or circuit breaker capable of being pad-
locked.
• Ground fault protection.
• Over-voltage and under-voltage protection.
• 3-phase sensing motor over current protection.
• 3-phase sensing input over current protection.
• Single phase protection.
• Insensitive to phase rotation.
• Over temperature protection.
• IEEE Standard 519-1992 compliance.
• Digital readout at the chiller unit control panel of output frequency, output voltage,
3-phase input current, 3-phase output current, input kVA, Kilowatts and Kilowatt-
hours, input voltage THD, input current TDD, self-diagnostic service parameters.
Separate meters for this information will not be acceptable.