Johnson Controls YORK YVAM 0350, Operation & Maintenance Manual

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Figure 49: Smart sensor system components location
Callout Description
A Smart sensor board mounted behind door rail
B Smart sensors
Note: Variable speed drive model HYP0490 shown, other models are similar.
OptiSpeed compressor drive and chiller operation (0490B
amp models)
When the chiller enters a start command, the OSCD is commanded to pre-charge. The pre-charge
contactor closes and slowly charges the DC Bus capacitors through the pre-charge resistors. This is
called the pre-charge period, which lasts for 12 seconds. When the 12-second time period expires,
the supply contactor closes and the pre-charge contactor opens. The supply and pre-charge
contactors remain in this state for the duration of the run cycle. The OSCD logic board provides the
commands for the supply and pre-charge contactors.
All models of HYP drives control the motor in the same manner for a normal stop command.
YVAM Control Center 120