Minimum Vsd Compressor Start/Stop Frequency; Minimum Vsd Start Frequency; Minimum Vsd Run Frequency; Fig 37 - Minimum Vsd Start Frequency - York YCAV0267E Installation Operation & Maintenance

OPERATION
MINIMUM VSD COMPRESSOR START/RUN FREQUENCY

MINIMUM VSD START FREQUENCY

The Minimum VSD Compressor Start Frequency is
based on ambient temperature and determines the
frequency (speed) the compressor(s) is ramped to at start.
At higher ambients, higher speeds are needed to provide
adequate motor cooling. At low ambients, higher motor
speeds are needed to develop oil pressure differential at
start. The temperature ranges and the associated start
frequency follows the guidelines below:
· If the ambient temperature is 25°F or less, the
Minimum VSD Start Frequency will be
70 Hz.
· If the ambient temperature is 26-40 °F, the
Minimum VSD Start Frequency is 60 HZ.
· If the ambient temperature is 41-110 °F, the
Minimum VSD Start Frequency will be
50 Hz.
· If the ambient is 110-125 °F, the Minimum VSD
Start Frequency is scaled according to the
following formula:
(3X Ambient Temperature)-280°F.
The formula is also represented by the graph in FIG.
37.
100
95
90
85
80
75
70
65
60
55
50
45
40
105 110 115
Ambient Temperature (°F)
NOTE: The graph above also illustrates the scaled frequency:
FIG. 37 - MINIMUM VSD START FREQUENCY
· A b o v e 1 2 5 ° F, t h e m i n i m u m V S D S t a r t
Frequency is 95 Hz.
210
120 125 130
LD10627

MINIMUM VSD RUN FREQUENCY

The Minimum VSD Compressor Run Frequency is based
on ambient temperature and determines the minimum
frequency (speed) the compressor(s) is permitted to run
as the system unloads. At high ambients, higher motor
speeds are needed to cool the compressor motor. The
temperature ranges and the associated start frequency
follows the guidelines below:
· If the ambient temperature is <110°F, the Minimum
VSD Run Frequency will be 50 Hz.
· If the ambient is 110-125°F, the Minimum VSD
Run Frequency is scaled according to the following
formula:
(3X Ambient Temperature) -280°F.
The formula is also represented by the graph in FIG.
38.
100
95
90
85
80
75
70
65
60
55
50
45
40
105 110 115
Ambient Temperature (°F)
NOTE: The graph above also illustrates the scaled frequency:
FIG. 38 - MINIMUM VSD RUN FREQUENCY
· If the ambient temperature is >125°F, the Minimum
VSD Run Frequency will be 95 Hz.
FORM 201.21-NM3 (616)
120 125 130
LD10628
JOHNSON CONTROLS