Micro Panel Contents

set to the saturated refrigerant pressure equivalent to 18°F (10°C) below the lowest temperature of the pro- grammed chilled liquid Control Range (Section 6).

To program the Suction Pressure Cutout, key in the re- quired setting and press the Enter key to store the value into memory and scroll the next display.

High Ambient Temperature Cutout

H I G H A M B I E N T

T E M P

C U T O U T = 1 3 0

. 0 ° F

 

 

The High Ambient Cutout is used to select the ambient temperature above which the chiller may not operate. If the ambient temperature rises 1°F (.5°C) above this point, the chiller will shut down. Restart will occur au- tomatically, when temperature falls more than 2°F (1°C) below the cutout and cooling demand is present.

This cutout is normally set at 130°F (54°C) to allow op- eration to the absolute maximum temperature capability of the electromechanical components; however, values between 100.0 - 130.0°F (38 - 54°C) are accepted.

To program the High Ambient Cutout, key in the re- quired setting and press the Enter key to store the value into memory and scroll to the next display.

Low Ambient Temperature Cutout

L O W A M B I E N T

T E M P

C U T O U T =

2 5 . 0 ° F

 

 

 

The Low Ambient Cutout is used to select the ambient temperature below which the chiller may not operate. If the ambient temperature falls 1°F (.5°C) below this point, the chiller will shut down. Restart will occur automatically, when temperature rises more than 2°F (2ºC) above the cutout and cooling demand is present (see also Section 2.5 page 139).

If the SW1 Dip Switch on the Microprocessor Board is set for “Standard Ambient Control” (see Section 3.7) the low ambient cutout is set at 25°F (-4°C) and is NOT programmable. If the Dip Switch is set for “Low Ambient Control”, programming of the cutout between

00.0- 50.0°F (-17.8 - 10°C) is allowed. This allows higher values than 25°F (-4°C) to be programmed to shut down the chiller when other cooling methods become operational. Values below 25°F (-4°C) can be used for applications requiring chiller operation at lower temperatures. The chiller will not operate below 0ºF (-17.8ºC).

FORM 201.19-NM1 (204)

To program the Low Ambient Cutout, key in the required setting and press the Enter key to store the value into memory and scroll to the next display.

Low Leaving Liquid Temperature Cutout

L E A V I N G L I Q U

I

D T E M P

C U T O U T =

3 6

.

0 ° F

 

 

 

 

The Low Leaving Liquid Temperature Cutout protects the evaporator from damage due to ice build up caused by operation below the chilled liquid freezing point.

If the leaving chilled liquid temperature (water or glycol) drops below the cutout point, the chiller will shut down. The chiller will restart automatically when temperature rises more than 4°F (2°C) above the cutout point and cooling demand exists.

If the Dip Switch on the microprocessor board is set for “Water Cooling” (see Section 3.7, page 146) the cutout is automatically set at 36°F (2°C) and cannot be reprogrammed. If the Switch is set for “Brine Cooling” (glycol) the cutout can be programmed between 08.0

-36.0°F (-13 to -2°C). The cutout should normally be set to 4°F (2°C) below the setpoint minus the range, i.e. 34°F (setpoint) – 2°F (range) - 4°F = 28°F (see Section 6, page 158).

To program the Leaving Liquid Temperature Cutout, key in the required setting and press the Enter key to store the value into memory and scroll to the next display.

High Motor Current Unload Point

H I G H M O T O R C U R R E N T U N L O A D = 1 0 5 % F L A

The Motor Current Unload point is used to avoid a high motor current safety shutdown by unloading a compressor, if current draw approaches the maximum limit cutout value. The chiller can then continue to run automatically at reduced capacity until the cause of the excessive current is attended to.

The micro will accept between 30 - 105% for the unload point. The motor current safety will shut the compressor down whenever current exceeds 115%.

If the programmable limit is set between 100% and 105% of full load current, this feature will protect against excessive current causing compressor shutdown due to extremely high ambient, high chilled liquid tem- perature, and condenser malfunction caused by dirt or fan problems.

168

YORK INTERNATIONAL

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York YCAS0130 manual Low Leaving Liquid Temperature Cutout, High Motor Current Unload Point, 168