York YD A, Operating & Maintenance, Page: 21 / 52

JOHNSON CONTROLS
21
SECTION 1 – DESCRIPTION OF SYSTEM AND FUNDAMENTALS OF OPERATION
FORM 160.69-O2
ISSUE DATE: 9/30/2020
1
Are Compressor
Motor Currents
Equal within 20%
Are vanes on the lower current
compressor open more than the
high current compressor?
Chiller Running
Two Compressor Mode.
Lead Compressor controlling LChWT
Lag Compressor following current of
Lead
No
Yes
No
Yes
Close Compressor Pre-rotation Vane
Motors
No
Have # of Total Surge Counts
Exceeded the # allowed within
time period setting
Stop and Lockout the lag compressor
Provide screen warning
Yes
Anti-Surge Control Algorithm
User Programmable:
Number of Surge Counts Allowed
(Default 3, range 2 to 8)
Count Window time period
(Default 60 min, range 15 to 120)
Increment Total Surge Count
YD Dual Compressor Chiller
FIGURE 2 – CHILLER OPERATION FLOW CHART - (CONT'D)
LD10493