JOHNSON CONTROLS
208
FORM 201.23-NM2
ISSUE DATE: 09/25/2020
SECTION 7 - OPERATION
TABLE 12 - VSD BASEPLATE TEMPERATURE
LOAD LIMITING/UNLOADING
VSD BASEPLATE TEMPERATURE UN-LOADING
Baseplate Temp. is between
Cutout- 8ºF & Cutout- 4ºF
0 Hz
Baseplate Temp. Cutout- 3.6ºF 1 Hz
Baseplate Temp. Cutout- 3.2ºF 2 Hz
Baseplate Temp. Cutout- 2.8ºF 3 Hz
Baseplate Temp. Cutout- 2.4ºF 4 Hz
Baseplate Temp. Cutout- 2.0ºF 5 Hz
Baseplate Temp. Cutout- 1.6ºF 6 Hz
Baseplate Temp. Cutout- 1.2ºF 7 Hz
Baseplate Temp. Cutout- 0.8ºF 8 Hz
Baseplate Temp. Cutout- 0.4ºF 9 Hz
Baseplate Temp. Cutout 10 Hz
FLASH TANK DRAIN AND FEED VALVE
CONTROLLER
Valve Controller and Control Algorithm
Operation
The Flash Tank Feed and Drain Valve PI Controller(s)
plays a dual role of supplying drive signals to control
the opening and closing of both the Flash Tank Feed
and Drain Valves. These valves control the liquid level
in the flash tank and the suction superheat of the com-
pressor. The Flash Tank Feed and Drain Valve Con-
troller receive analog signals from the Chiller Control
Board to position the Feed and Drain Valves.
The Chiller Control Board PI (Proportional plus In-
tegral) control algorithm in the Chiller Control Board
software determines the open % for the Drain and Feed
valves. A D/A converter on the Chiller Control Board
converts the 0% to 110.0% signal to an output voltage
between 0 VDC and 10.28 VDC and sends it to the
Drain and Feed Controller. This voltage is then con-
verted to a valve position by the Drain and Feed Valve
Controller and a 2 phase (4 wire), signal drives the
Feed Valve open or closed. Power for the Valve Con-
troller comes from a 30 VDC supply from the Chiller
Control Board.
FIGURE 53 - FLASH TANK DRAIN AND FEED VALVE CONTROLLER
LD10619
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