York J Series - Binary Input Operation

JOHNSON CONTROLS
68
FORM 100.50-NOM7 (808)
Service
BINARY INPUT OPERATION
This section describes the control operation of the
sixteen (16) binary inputs. The Binary inputs are also
described in the I/O tables in Table 15.
The unit control is equipped with sixteen (16) binary in-
puts. The binary inputs can be classied into two types,
control and status inputs. Control inputs will be used by
the control to switch control states. For example, BI #7
(J8, Pin 1), Supply Fan (G), will signal to the control
to turn the supply fan ON or OFF. Status inputs will
be used by the control to signal the status of, or prove,
certain safety circuits. For example, BI #11 (J9, pin 1),
Supply Fan Status, will signal to the control when the
Supply Fan is ON and thus prove the operation of the
Supply Fan.
The binary input status is dened as:
• 24VAC detected by the input - the input is “pres-
ent”.
• No voltage detected by the input or voltage below
the 24VAC detection threshold - the input signal is
“not present”.
The fault conditions and responses for all binary inputs
with associated faults are given in Table 17.
BI #1, 2, & 3 - Compressor Circuit #1, 2, & 3 Sta-
tus Inputs
Each refrigeration circuit consists of two compressors
arranged in tandem. For safety, each circuit is equipped
with a “compressor safety chain”, which consists of
high and low pressure safeties and overloads for each
compressor motor. The electrical contacts for the safety
devices in this chain will be connected in series with the
entire circuit connected to a 24VAC source. In a “safe”
state, the electrical contacts from all safety devices
will be closed. The “compressor safety chain” for each
compressor circuit will be connected to the following
binary inputs:
• Compressor circuit #1 – BI #1 - Compressors 1 &
2, 40-ton.
• Compressor circuit #2 – BI #2 - Compressors 3 &
4, 40-ton.
• Compressor circuit #3 – BI #3 (not used).
High Pressure Switch settings are:
open @ 625 +/- 10 psig
close @ 500 +/- 10 psig
Low Pressure Switch settings are:
open @ 50 +/- 5 psig.
close @ 71 +/- 5 psig.
For normal operation, the Compressor Circuit Status
inputs must be present (24VAC to input). During low
ambient conditions, when no compressor is ON, the
Low Pressure safety may be tripped (open) indicating
an unsafe condition. To avoid nuisance errors:
• The control will monitor the Compressor Circuit
Status inputs only when a compressor from that
circuit is operating.
• When any compressor is started, the control will
ignore the associated Compressor Circuit Status
input for 30 seconds.
• After the 30 second delay, if the status input is not
present for more than 250 ms, the control will de-
energize all compressors operating in that circuit
and declare a Comp Safety Trip fault.
• The control will then wait ten (10) minutes before
re-energizing the compressors in the tripped circuit,
if still required.
Each Compressor Status Circuit input has two trip
counters. Both counters will start at zero.
Counter #1 will:
• Increment by 1 any time a trip occurs.
• Be reset to zero counts if one or both compressors
on the circuit are ON for 1 hour without a Comp
Safety Trip.
Counter #2 will:
• Increment by 1 any time a trip occurs and both
compressors are operating.
• Be reset to zero counts if both compressors on the
circuit are ON for 1 hour without a Comp Safety
Trip.
If the count of either Compressor Status counter on a
compressor circuit = 3, the compressors on the circuit
are shut down and locked out and a Compressor Safety
Lockout (Comp Safety L/O) fault is declared.
Compressor Safety Lockout(s) will reset through power
cycling of the controller.