Table 12 - Vsd Operating Display Parameters - York YCAV0267E Installation Operation & Maintenance

VSD OPERATION AND CONTROLS (CON'T)
Current Sensing and Scaling
Individual current transformers on each leg sense three
phases of output current on each compressor. These sig-
nals are buffered, divided by 2, and filtered by an RMS
to DC converter. The highest of the currents in the three
phases of each compressor leaving the RMS converters
is then sent to an A-D converter scaled, monitored by
the VSD Logic Board overload and high current protec-
tion circuitry, and sent to the Chiller Control Board for
display as the compressor current.
In order to set the motor overload level (determined by
the setting of the OVERLOAD ADJUST potentiometer
on the VSD Logic Board), the voltage level on the wip-
ers of the four OVERLOAD ADJUST potentiometers is
continuously sensed by the VSD Logic Board for current
protection and sent to the Chiller Control Board for both
display purposes and for current limiting control. This
parameter is the 105% FLA value.

TABLE 12 - VSD OPERATING DISPLAY PARAMETERS

Highest Phase of Compressor
Motor Current in Amperes RMS
(105% FLA potentiometer setting)
DC Bus Voltage in DC Volts
VSD Internal Ambient Temperature
IGBT Power Assembly Power Module
Highest Baseplate Temperature
JOHNSON CONTROLS
DATA
(per Compressor)
VSD Output Frequency
Motor Overload Setting
in amperes RMS
(per Compressor)
(maximum of 2)
(maximum of 2)
Pre-Charge Enable Signal
(maximum of 2)
VSD cooling Fan/Pump
Compressor Run Status
(maximum of 4)
VSD Transmitted Operating parameters
VSD operating parameters will be transmitted to the
Chiller Control Board over the RS-485 communica-
tions link between the 2 boards. These values will be
displayed on the control panel display. The data and
display format are outlined in the TABLE 12 below:
DISPLAY
FORMAT
XXX Amps
XXX.X Hz
XXX Amps
XXX Volts
XXX.XºF
(or ºC)
XXX.XºF
(or ºC)
On or OFF
On or OFF
On or OFF
FORM 201.21-NM3 (616)
8
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