JOHNSON CONTROLS
115
SECTION 5 – SEQUENCE OF OPERATION
FORM 145.05-NOM7
ISSUE DATE: 10/31/2019
5
The # symbol varies to match the compressor number
the data is recorded for (A, B, C, etc.).
Compressor Status Display
The compressor status always displays the following:
• “READY” – Indicates the compressor is OFF and
ready for use
• “COMP ON” – Indicates a binary output is sent
for compressor operation
• “OFF-ASCD” – Indicates the compressor is OFF
but not ready to run because the minimum OFF
time of 3-1/2 minutes has not been met
• “USER DISABLED” – Indicates the compressor
has been disabled through the PROGRAM key
• “SAFETY TRIP 1” – Indicates the compressor has
experienced an initial Compressor Safety Circuit
trip. See
Compressor Safety Circuit on page 115
• “SAFETY TRIP 2” - Indicates the compressor has
experienced a second Compressor Safety Circuit
trip within 120 minutes. See
.
• “SAFETY LOCKOUT” – Indicates the compres-
sor has experienced a third Compressor Safety
Circuit trip within 120 minutes and is locked out.
Compressor Safety Circuit on page 115
• “LOW PRESS LOCKOUT” – Indicates the suc-
tion pressure for the compressor had fallen below
the SUCTION PRESSURE LIMIT and remained
at that level beyond the calculated TRIPTIME.
See
Low Pressure Monitoring on page 117
for a
detailed explanation.
• “INHIBITED” – Indicates one of the following is
active:
• “WRN-LOW WATER TEMP”
• “WRN-LOW WATER FLOW”
• “WRN-SUCT PRESS XDCR#”
• “WRN-DISC PRESS XDCR#”
• “LOCKOUT-LOW PRESS SYS #”
• “SUPPLY FAN STATUS”
As conditions can occur that more than one of the
above criteria was active concurrently, the following
priority level in
is used to de-
termine which of the above to display. The greater the
number, the higher the priority. The highest priority
criteria is displayed.
TABLE 22 -
COMPRESSOR STATUS PRIORITY
LEVEL
PRIORITY LEVEL
MESSAGE
1
Ready
2
Comp On
3
Off-Ascd
4
Inhibited
5
Safety Trip 1
6
Safety Trip 2
7
User Disabled
8
Safety Lockout
9
Low Press Lockout
Compressor Safety Circuit
Each compressor system is equipped with external cir-
cuitry monitoring hardware intended to protect the com-
pressors in case the operating characteristics of the refrig-
erant system fall outside the safe operating envelope for
identifies which
of the following safeties are contained in the system.
On 25–60 ton units, the Compressor A
Safety Chain Status shows as FAULTED
until the compressor starts. This is a nor-
mal condition when the unit is in OCC
STANDBY or UNOCC STANDBY mode.
On 70–105 ton units, the Compressor A
Safety Chain Status should always show
OKAY unless FAULTED.
High Pressure Cutout
The high pressure cutout is mounted on the discharge
line and is an automatic reset device. The switch opens
at 500 PSIG and resets at 375 PSIG.
External Compressor Motor Protector
The external motor protector is contained in the com-
pressor control box and monitors a sensor imbedded in
the windings of the compressor. If the protection mod-
ule opens, it takes 30 minutes plus or minus 5 minutes
for it to reset depending on how hot the motor is and
the ambient temperature. To troubleshoot the protector,
check the resistance of the sensor:
• Normal resistance is 250 to 2250 Ohms
• Trip resistance is more than 4500 Ohms plus or
minus 20%
• Reset resistance is less than 2750 Ohms