YORK INTERNATIONAL 53
FORM 150.40-NM25
DUAL CIRCUIT UNITS
BOTH SYSTEMS DOWN ON A FAULT:
In a situation where both systems are down on a fault,
the “F” code will be displayed and the associated stored
data will apply to both system conditions at the time of
the 1st Fault. A “.” will appear next to the “F” (“F.”), in-
dicating that both systems are down on a Fault.
After clearing the 1st Fault, an “F” code will still be dis-
played, but without the “.”. The stored data will still be
that which was stored at the time of the 1st Fault. This
will probably not provide any levels which were out of
the allowed operating range for the second Fault, un-
less the Fault related to low leaving water temperature
or ambient temperature which affects both systems. This
type of Fault occurs simultaneously on both systems and
will require both System Switches to simultaneously be
placed in the off position to clear. Restart can only be
accomplished after temperature falls within allowable lim-
its.
After clearing the Fault(s), placing the SYSTEM
Switch(es) to the ON position will cause a normal start
sequence to begin unless the problem causing the origi-
nal trouble is still causing safety thresholds to be ex-
ceeded. If this occurs, an “F” code will then reappear.
NOTE: The trouble may not immediately show up and
the system may run for awhile.
IMPORTANT
Anytime a system shuts down on a Fault, steps should
be taken to find and eliminate the cause of the problem
before attempting to restart the system.
The operator should also be aware that before the unit
will display an “F” code, the problem system has probably
exceeded safety thresholds and has shut down twice
and restarted within the last 90 minutes. This insures
that the system will not shut down and lock out on a
nuisance trip if the system is operating under marginal
conditions.
MANUAL RESET FAULTS
(3 Faults and Lockout)
The system will shut down instantly when a Manual Re-
set Fault is sensed, but it will allow automatic restart
until it sees a total of any 3 Faults in a 90-minute period.
A 90-minute counter is started as soon as the 1st Fault
occurs. If 2 more faults do not occur in the next 90 min-
utes, the counter is reset to “0”. Fault codes F1 – F8,
refer to Manual Reset Faults.
After a Manual Reset Fault, restart cannot be expected
until the anti-recycle timers time out. No display (“F”
Code) will be indicated during the first two faults except
for a letter code telling the operator the anti-recycle timer
is in effect. After 3 faults, an “F” code will be displayed
and the system will lockout and not restart. The fault
can be cleared and the compressor restarted by placing
the System Off/On Switch to the “OFF” position. How-
ever, another fault will shut down the system and an “F”
code will be displayed. The system will continue to shut
down after restart on every Fault with an “F” code until
the problem system runs without faulting for 90 minutes
or until power is cycled. Recycling power will reset the
counter to “0”.
F1 (System 1) or F5 (System 2) Fault
Low Or High Motor Current
Analog signals are provided to the Analog Input Board
and then to the Micro-Board by the Motor Current Boards
(MCB) which get info from 6 current transformers (C.T.’s:
3 per system). A signal of 4VDC = 100% FLA Current.
The affected system shuts down if the signal is < 1.2VDC
(< 24% FLA) or > 4.6VDC (>115% FLA) when Run Time
>4 sec. This protection assures that both contactors are
energized, all C.T.’s are connected and operating, and
that the motor is not drawing excessive as well as too
little current. An F1 (Sys 1) or an F5 (Sys 2) will be dis-
played for this safety.
Anytime an external High Discharge Pressure Cut-Out
or Thermal Motor Overload Sensor contacts open, the
affected system will shut down. The automatic reset on
the sensor must automatically reset before the system
can be restarted. The external HP cutout is set at 395
PSI (2721 kPa). An F1 (Sys 1) or an F5 (Sys 2) will be
displayed for either safety.
NOTE: These are the same codes displayed for a motor
current (power) Fault. This occurs because these
safeties do not allow the motor contactor to en-
ergize, causing motor current to be “0”. When a
system is to start, the Micro sends the start sig-
nal to the contactor pilot relay on the Relay Out-
put Board. The pilot relay closes a contact which
applies 115VAC to the motor contactor. If the High
Pressure C.O. or motor protector opens, their
contacts which are wired in series with the pilot
relay contacts keep 115VAC from being applied
to the motor contactor. The contactor will not pull
in as the Micro commands or will drop out if pulled
in so the system will shut down on low motor
current. Whenever an F1 or F5 Fault occurs,
check discharge pressure at the time of the fault
and motor current at the time of fault, which would
indicate a H.P. Cut-out or motor protector con-
tact which is open.
F2 (System 1) or F6 (System 2) Fault
Low Oil Pressure
Analog signals are sent to the Analog Input Board then
to Micro Board from the suction and oil pressure trans-
F
2
F
1
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