Section 4 - Vsd Operation; Optispeed Compressor Drive Overview; Optispeed Compressor Drive Features - York YMC2 Operation And Maintenance

FORM 160.84-OM1
ISSUE DATE: 9/21/2017
OPTISPEED COMPRESSOR DRIVE
OVERVIEW
The new YORK OptiSpeed Compressor Drive (OSCD)
is specifically designed for the application of driving
a permanent magnet high speed motor with magnetic
bearings used on the YORK Model YMC
Liquid Chiller. This type of design allows the chiller
to be designed as a complete system, and take full
advantage of the strengths of each major component
within the system. This method of design is a superior
approach to using general purpose components off the
shelf that may not work well together.
This new OSCD design builds on the successes of pre-
vious designs of being chiller mounted, provide for
high levels of energy savings, great integration with
the chiller control center, liquid cooled, shell and tube
heat exchanger, use of fast switching power modules,
high reliability, and ease of service.
New features include:
• The option of a circuit breaker or disconnect
switch.
• Ground fault detection even when a disconnect
switch is selected.
• Direct liquid cooling of power modules.
• A more accessible cooling system.
• Variable voltage input.
• High speed direct drive motor.
• The Harmonic filter is standard on all models.
• Modular lighter weight power units that can be re-
paired in the field without complete replacement.
• Ease of maintenance and setup.
OPTISPEED COMPRESSOR DRIVE
FEATURES
The new drive design is current available in the fol-
lowing models: HYP0490, HYP0490A, HYP0612A,
HYP0730A, HYP0774 and HYP1278A. The opera-
tion of each drive is identical except for the precharge
of the 0490A, 0612A, 0730A and 1278A amp models.
Each drive model has a dedicated drive logic board.
The drive logic board cannot be switched between the
drive models. There are basically 2 different power as-
semblies used between the 5 drive designs. The 0490,
0490A 0612A and the 0730A amp drives use a single
power assembly that contains all of the power devices
required for the 3 phases of input and output. The 0774
JOHNSON CONTROLS

SECTION 4 - VSD OPERATION

and the 1278A amp drives have three power assem-
blies. Each power assembly contains all of the power
devices required for one phase of input and output.
Centrifugal
2
For the first time, the OSCD is offered with a discon-
nect switch without giving up the ability to detect a
ground fault. The OSCD contains 3 input current sen-
sors that will provide the information for the drive log-
ic board to detect a ground fault condition.
Direct liquid cooling is a much more efficient way of
removing heat from the OSCD. This method also re-
duces the cooling load on the internal cooling coil. In
the past, YORK developed direct liquid cooling for the
inverter power modules, but today York is direct liquid
cooling the rectifier, inverter, input inductor, and the
output filter inductor.
The cooling system for the OSCD is greatly modified
to improve serviceability of the power electronics. Re-
pair of the power electronics no longer requires access
to the back of the drive except to drain the cooling sys-
tem. Also the use of a shell and tube heat exchanger is
standard on all models.
The OSCD can now be configured for many different
input voltage levels. Lower input voltages may de-rate
the input power rating of the OSCD, but the OSCD
will produce the same output voltage and will use the
same motor.
The Harmonic filter is no longer an option, and the
function of the Harmonic filter is included in a new
rectifier module. This type of arrangement for the rec-
tifier no longer requires a separate power unit for the
Harmonic filter. Also this rectifier is part of the power
unit for the inverter, thus reducing the number of parts
required and increasing reliability.
The new OSCD control system allows for high speed
operation of the compressor motor. This improvement
eliminates the need for a gear system between the com-
pressor motor and the compressor. Without a gear sys-
tem reliability and efficiency are improved.
The new power unit consists of a newly designed bus
capacitor, new light weight plastic cooling blocks, new
power module gate driver design, new rectifier mod-
ule, and the cooling system is connected to the front of
the power unit for reduce down time and service cost.
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