Bard PA13421-B Start UP and Operation, Three Phase Scroll Compressor Start UP Information

START UP AND OPERATION

THREE PHASE SCROLL COMPRESSOR START UP INFORMATION

(PA1336, 42, 48 and 60 Models)

Scroll compressors, like several other types of compressors, will only compress in one rotational direction. Direction of rotation is not an issue with single phase compressors since they will always start and run in the proper direction.

However, three phase compressors will rotate in either direction depending upon phasing of the power. Since there is a 50-50 chance of connecting power in such a way as to cause rotation in the reverse direction, verification of proper rotation must be made. Verification of proper rotation direction is made by observing that suction pressure drops and discharge pressure rises when the compressor is energized. Reverse rotation also results in an elevated sound level over that with correct rotation, as well as, substantially reduced current draw compared to tabulated values.

position and the blower is already in operation, then the motor will ramp up to the required speed for cooling.

HEATING (1st Stage) – On a call for heating from the room thermostat (circuit R-W1 makes), the blower will energize (circuit R-G is automatic when R-W1 makes). This will place the system into heating operation to maintain the thermostat set temperature. Note that if the “Fan” switch on the room thermostat is in the “On” position and the blower is already in operation, then the motor will ramp up to the required speed for heating.

HEATING (2nd Stage) – If the operation of the 1st Stage electric heaters will not maintain the set room temperature, then the thermostat will call for additional heat to help maintain the set temperature. On a call for second stage heating from the room thermostat (circuit R-W2 makes), additional electric heaters will be energized if installed.

Verification of proper rotation must be made at the time the equipment is put into service. If improper rotation is corrected at this time there will be no negative impact on the durability of the compressor. However, reverse operation for over one hour may have a negative impact on the bearing due to oil pump out.

NOTE: If compressor is allowed to run in reverse rotation for several minutes the compressor’s internal protector will trip.

All three phase scroll compressors are wired identically internally. As a result, once the correct phasing is determined for a specific system or installation, connecting properly phased power leads to the same Fusite terminals should maintain proper rotation direction.

The direction of rotation of the motor may be changed by reversing any two line connections to the unit.

SEQUENCE OF OPERATION

BLOWER ONLY – When the “Fan” switch on the room thermostat is placed in the “On” position (circuit R-G makes), the blower will energize and run until the “Fan” switch is placed back into the “Auto” position. This will allow for constant air circulation at a lower airflow during times when the unit is not in operation for cooling or heating.

COOLING – On a call for cooling from the room thermostat (circuit R-Y makes), the blower will energize (circuit R-G is automatic when R-Y makes) as well as the compressor, and outdoor fan motor. Note that if the “Fan” switch on the room thermostat is in the “On”

INDOOR BLOWER MOTOR

Some models feature a variable speed (ECM) motor providing high efficiency, low sound levels and soft start capabilities. The motor is self adjusting to provide the proper air flow rate at duct static pressures up to 0.50" WC without user adjustment or wiring changes.

On command from the wall thermostat the motor will start slowly and ramp up to full speed over a period of 10- 15 seconds.

When the thermostat is satisfied the blower will operate for approximately 1 minute, and then slow down and stop.

COMPRESSOR CONTROL MODULE

The compressor control is an anti-short cycle/lockout timer with high and low pressure switch monitoring and alarm output.

ADJUSTABLE DELAY-ON-MAKE AND BREAK TIMER

On a call for compressor operation the delay-on-make period begins which will be 10% of the delay-on-break setting. When the delay-on-make is complete and the high pressure switch (and low pressure switch if employed) is closed, the compressor contactor is energized. Upon shutdown the delay-on-break timer starts and prevents restart until the delay-on-break and delay-on-make periods have expired.

Manual	2100-467
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