Bard WA482 Spécifications télécharger pdf (Page 16)

Manual 2100-218

Page 14

THREE PHASE SCROLL COMPRESSOR

START UP INFORMATION

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.

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 ZR3 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 terminal should maintain proper rotation direction.

The direction of rotation of the compressor may be

changed by reversing any two line connections to the

unit.

CONDENSER FAN OPERATION

The condenser fan motor on 230/208 volt, one and three

phase, 60 HZ units is a two speed motor that comes

factory wired on high speed for peak performance. If

ambient conditions permit, it can be reconnected to low

speed (red wire) for lower sound level. See wiring

diagram.

50 HZ models must have fan wired on low speed. These

models are factory wired on low speed.

START UP

IMPORTANT INSTALLER NOTE

For improved start up performance wash the indoor coil

with a dish washing detergent.

CRANKCASE HEATERS

WA421 units are provided with compressor crankcase

heat. WA602 and WA482 units are not provided with

crankcase heat. These units utilize scroll compressors

which do not require crankcase heat in this application.

The WA421 models have an insertion well-type heater

located in the lower section of the compressor housing.

This is a self-regulating type heater that draws only

enough power to maintani the compressor at a safe

termperature on these units.

Some form of crankcase heat is essential to prevent liquid

refrigerant from migating to the compressor causing oil

pump out on compressor start up and possible valve

failure due to compressing a liquid.

The decal in Figure 9 is affixed to all WA421 units

detailing start up procedure. This is very important.

Please read carefully.

HIGH PRESSURE SWITCH

The WA482 and WA602 models are supplied with a

remote reset high pressure switch. If tripped, this

pressure switch may be reset by turning the themostat off

then back on again.

FIGURE 9

STARTING PROCEDURE

IMPORTANT

THESE PROCEDURES MUST BE FOLLOWED AT

INITIAL START UP AND AT ANY TIME POWER

HAS BEEN REMOVED FOR 12 HOURS OR

LONGER.

To prevent compressor damage which may result

from the presence of liquid refrigerant in the

compressor crankcase.

1. Make certain the room thermostat is in the “off”

position (the compressor is not to operate).

2. Apply power by closing the system disconnect

switch. This energizes the compressor heater

which evaporates the liquid refrigerant in the

crankcase.

3. Allow 4 hours or 60 minutes per pound of

refrigerant in the system as noted on the unit

rating plate, which ever is greater.

4. After properly elapsed time, the thermostat

may be set to operate the compressor.

5. Except as required for safety while servicing,

Do not open system disconnect switch.

7961-061

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Bard WA482 Spécifications Page 16

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