Capacity Compressor Cycling Screen; Figure 23 - Capacity Compressor Cycling - York YD Series Operation Manual

FORM 160.69-O1
ISSUE DATE: 9/30/2012
Overview
This screen allows the user to specify the chiller load
conditions under which the lag compressor is cycled on
and off. Both compressors are not started at the same
time. The lead compressor is started first. If it does not
meet the load requirements as established with the fol-
lowing setpoints, the lag compressor is started. After
the lag compressor is running, it will be shutdown if
the load decreases to the point established by the fol-
lowing setpoints. Parameters pertinent to chiller load-
ing are displayed. Also, compressor #1 or #2 can be
selected for lockout.
Display Only
Temperature Differential (Leaving Chilled Liquid
Temperature minus Setpoint)
Displays the difference between the Leaving Chilled
Liquid Temperature and the Leaving Chilled Liquid
Temperature Setpoint.
Delta T Rate
Displays the rate of change of the Leaving Chilled Liq-
uid Temperature as "X.X ºF/Minute". Value displayed
represents a five-point rolling average obtained as fol-
lows: After the first 3 minutes of chiller run time, the
Leaving Chilled Liquid Temperature is sampled once
every minute. The previous reading is subtracted from
the present reading and the last 5 results are averaged
to obtain a five-point rolling average. Displayed as
zero when chiller is not running.
LEAVING CHILLED LIQUID CONTROL

FIGURE 23 - CAPACITY COMPRESSOR CYCLING

JOHNSON CONTROLS

CAPACITY COMPRESSOR CYCLING SCREEN

SECTION 2 – OPTIVIEW CONTROL CENTER
Lead % Full Load Amps
Displays the motor current of the lead compressor as
a percentage of the full load amps of that compressor
motor.
Lead Pre-rotation Vanes Position
Displays the position of the lead compressor pre-rota-
tion vanes position.
Lead Variable Geometry Diffuser Position
Displays the position of the lead compressor Variable
Geometry Diffuser.
Lag %Full Load Amps
Displays the motor current of the lag compressor as
a percentage of the full load amps of that compressor
motor.
Lag Pre-rotation Vanes Position
Displays the position of the lag compressor pre-rota-
tion vanes position.
Lag Variable Geometry Diffuser Position
Displays the position of the lag compressor Variable
Geometry Diffuser.
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