FORM 150.66-NM2
ISSUE DATE: 09/25/2020
105
JOHNSON CONTROLS
SECTION 7 - UNIT CONTROlS
7
This safety will shut down a system if either suction
temperature or suction pressure sensors read out of
range high or low. This condition must be present for 3
seconds to cause a system shutdown. The safety locks
out a system after the first fault and will not allow
automatic restarting.
Unit Safeties
Unit safeties are faults that cause all running compressors
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.
The Low Ambient Temp Cutout is a safety shutdown
designed to protect the chiller from operating in a low
ambient condition. If the outdoor ambient temperature
falls below the programmable cutout, the chiller will
shut down. Restart can occur when temperature rises
2°F above the cutoff.
The Low Leaving Chilled Liquid Temp Cutout protects
the chiller form an evaporator freeze-up should the
chilled liquid temperature drop below the freeze point.
This situation could occur under low flow conditions
or if the micro panel setpoint values are improperly
programmed. Anytime the leaving chilled liquid
temperature (water or glycol) drops below the cutout
point, the chiller will shutdown. Restart can occur when
chilled liquid temperature rises 2°F above the cutout.
The Under Voltage Safety ensures that the system
is not operated at voltages where malfunction of the
microprocessor 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 counting down.
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 according
to compressor or unit RLA.
Restart will occur after the anti-recycle timer times
out.
UNIT WARNING
The following messages are not unit safeties and will not
be logged to the history buffer. They are
unit warnings
and will not auto-restart. Operator intervention is
required to allow a restart of the chiller.
The Low Battery Warning can only occur at unit
power-up. On micro panel power-up, the RTC battery
is checked. If a low battery is found, all programmed
setpoints, program values, options, time, schedule, and
history buffers will be lost. These values will all be reset
to their default values which may not be the desired
operating values. Once a faulty battery is detected,
the unit will be prevented from running until the
PROGRAM key is pressed. Once PROGRAM is pressed
the anti-recycle timers will be set to the programmed
anti-recycle time to allow the operator time to check
setpoints, and if necessary, reprogram programmable
values and options.
If a low battery is detected, it should be replaced as
soon as possible. The programmed values will all be
lost and the unit will be prevented from running on
the next power interruption. The RTC/battery (031-
02565-000) is located at U5 on the IPU microboard
(031-02630-000).
This indicates the condensing unit jumper is installed
between J4-11 and J4-6, on a liquid chiller. This jumper
must be removed to operate the chiller.
U N I T F A U L T :
L O W A M B I E N T T E M P
U
N I T F A U L T :
1 1 5 V A C U N D E R V O L T A G E
U N I T F A U L T :
L O W L I Q U I D T E M P
! ! L O W B A T T E R Y ! !
C H E C K P R O G / S E T P / O P T N
U N I T F A U L T :
H I G H M T R C U R R
I N C O R R E C T
U N I T T Y P E
Summary of Contents for YCAL0012EC
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