York MILLENNIUM YB Series, Эксплуатация и техническое обслуживание

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YORK INTERNATIONAL
LD00167
FIG. 15 – KEYPAD – SERVICE KEYS LOCATION
SERVICE KEYS
The “ SERVICE ” keys are provided for the service tech-
nician’s use when performing routine maintenance or when
troubleshooting the system. The “ WARNING RESET ” and
“ PREROTATION VANES/ENGINE SPEED ” keys are en-
abled in “ SERVICE ” mode only. The remainder of the SER-
VICE keys are enabled in “ SERVICE ”, “ LOCAL ” or “ RE-
MOTE ” mode.
REFRIGERANT LEVEL CONTROL
1. Description
2. Automatic operation
3. Manual Operation
4. Fixed Position Operation
(Refer to the YORK Service manual on setting the pa-
rameters in this section.)
The subject chillers can now be ordered with an optional
condenser refrigerant level control consisting of:
A. Level control actuator
B. Refrigerant level sensor, R134a - 025-31712-000
C. Refrigerant level control board, 031-01655-000
The refrigerant level sensor senses the actual refrigerant
level in the condenser and outputs an analog voltage to
the micro board that represents this level. During unit
run, the micro board modulates the refrigerant level ac-
tuator that is connected to the variable orifice to maintain
the condenser refrigerant level to the setpoint level pro-
grammed into the MicroComputer Control Center by the
field service technician.
The refrigerant level sensor outputs a voltage from TB-3
over the range of 0.24VDC to 4.31VDC corresponding to
a level of 0% to 100%. At the end of each level control
period (programmable from 1.0 to 5.0 seconds), the mi-
cro board drives the close output (J10-1) or open output
(J10-3) to <1 VDC for an appropriate number of seconds
to turn on the close or open triac driver on the “refrigerant
level control” board. When the appropriate triac turns on,
it shorts the close (2) or open (3) coil of the “level control
actuator” to common terminal (X). This causes the ac-
tuator to turn in the desired direction to open or close the
refrigerant level valve.
“AUTOMATIC” OPERATION
The entire chiller run time is divided into level control
periods. The level control period is programmable over
the range of 1.0 to 5.0 seconds. Upon entering “system
run,” the level control period timer is started. When it has
elapsed, it is again initiated. Each time the level control
period has elapsed, it is restarted.