Quantech QCC2015CEE Installation, Operation And Maintenance Manual page 108

SECTION 7 – UNIT CONTROLS
The compressor is also equipped with a discharge
temperature sensor for the purpose of sensing inter-
nal scroll temperature. This sensor protects the scrolls
from overheating due to inadequate cooling that may
occur when refrigerant charge is low, or superheat is
too high.
When the sensor senses a high temperature, it opens
the motor protector circuit in the compressor causing
the compressor to shut down.
During the first two faults an MP/HP INHIBIT message
will be displayed and the system will not be locked out.
Only after the third fault in 90 minutes will the MP/
HPCO FAULT message be displayed.
Whenever the motor protector or discharge sensor
shuts down a compressor and the system, the inter-
nal compressor contacts will open for a period of 30
minutes to ensure that the motor or scroll temperatures
have time to dissipate the heat and cool down.
After 30 minutes, the contacts will close and the sys-
tem will be permitted to restart. The microboard will
not try to restart the compressors in a system that shuts
down on this safety for a period of 30 minutes to allow
the internal compressor to time out.
During the 30 minute timeout, the MP/HPCO INHIB
message will be displayed. The MP/HPCO fault will
only be displayed after 3 shutdowns in 90 minutes,
indicating the system is locked out and will not
restart.
S Y S 1 H I G H
S Y S 2 H I G H
When the System Current Feedback option is installed
and selected (Option 11 under OPTIONS key Current
Feedback), this safety will operate as follows. If the
actual feedback voltage of the system proportional to
currents exceeds the programmed trip voltage for 5
seconds, the system will shutdown.
108
M T R C U R R
M T R C U R R
Unit safeties
Unit safeties are faults that cause all running compres-
sors to be shut down. Unit faults are auto reset faults
in that the unit will be allowed to restart automatically
after the fault condition is no longer present.
U N I T
L O W A M B I E N T
The Low Ambient Temp Cutout is a safety shutdown
designed to protect the unit from operating in a low
ambient condition. If the outdoor ambient temperature
falls below the programmable cutout, the unit will shut
down. Restart can occur when temperature rises 2°F
above the cutoff.
U N I T
1 1 5 V A C U N D E R
The Under Voltage Safety ensures that the system is
not operated at voltages where malfunction of the mi-
croprocessor could result in system damage. When
the 115 VAC to the micro panel drops below a certain
level, a unit fault is initiated to safely shut down the
unit. Restart is allowed after the unit is fully powered
again and the anti-recycle timers have finished count-
ing down.
U N I T
H I G H M T R
When the CURRENT FEEDBACK ONE PER UNIT
option is selected under the OPTIONS key, the unit will
shut down when the voltage exceeds the programmed
trip voltage for 5 seconds.
The trip voltage is programmed at the factory accord-
ing to compressor or unit RLA.
Restart will occur after the anti-recycle timer times out.
Form QCC2-NM1
Issue Date: 5/20/2021
F A U L T :
T E M P
F A U L T :
V O L T A G E
F A U L T :
C U R R
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