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SECTION 7 - OPERATION
TABLE 12 - VSD BASEPLATE TEMPERATURE
LOAD LIMITING/UNLOADING
VSD BASEPLATE TEMPERATURE
Baseplate Temp. is between
Cutout- 8ºF & Cutout- 4ºF
Baseplate Temp. Cutout- 3.6ºF
Baseplate Temp. Cutout- 3.2ºF
Baseplate Temp. Cutout- 2.8ºF
Baseplate Temp. Cutout- 2.4ºF
Baseplate Temp. Cutout- 2.0ºF
Baseplate Temp. Cutout- 1.6ºF
Baseplate Temp. Cutout- 1.2ºF
Baseplate Temp. Cutout- 0.8ºF
Baseplate Temp. Cutout- 0.4ºF
Baseplate Temp. Cutout
FIGURE 53 - FLASH TANK DRAIN AND FEED VALVE CONTROLLER
208
FLASH TANK DRAIN AND FEED VALVE
CONTROLLER
UN-LOADING
Valve Controller and Control Algorithm
Operation
0 Hz
The Flash Tank Feed and Drain Valve PI Controller(s)
1 Hz
plays a dual role of supplying drive signals to control
2 Hz
the opening and closing of both the Flash Tank Feed
3 Hz
and Drain Valves. These valves control the liquid level
4 Hz
in the flash tank and the suction superheat of the com-
5 Hz
pressor. The Flash Tank Feed and Drain Valve Con-
troller receive analog signals from the Chiller Control
6 Hz
Board to position the Feed and Drain Valves.
7 Hz
8 Hz
The Chiller Control Board PI (Proportional plus In-
9 Hz
tegral) control algorithm in the Chiller Control Board
10 Hz
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.
FORM 201.23-NM2
ISSUE DATE: 09/25/2020
LD10619
JOHNSON CONTROLS
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