Carrier 50GX, 50GS instruction manual Transformer Protection, Pre-Start-Up

		LEGEND
FLA	—	Full Load Amps
LRA	—	Locked Rotor Amps	®
MCA	—	Minimum Circuit Amps
MOCP — Maximum Overcurrent Protection
RLA	—	Rated Load Amps
CKT BKR — Circuit Breaker

NOTES:

1.In compliance with NEC (National Electrical Code) requirements for multimotor and combination load equipment (refer to NEC Articles 430 and 440), the overcurrent protective device for the unit shall be Power Supply fuse . Canadian units may be fuse or circuit breaker.

2.Minimum wire size is based on 60 C copper wire. If other than 60 C wire is used, or if length exceeds wire length in table, determine size from NEC.

3.Unbalanced 3-Phase Supply Voltage

Never operate a motor where a phase imbalance in supply volt- age is greater than 2%. Use the following formula to determine the percentage of voltage imbalance.

%Voltage imbalance

=100 x max voltage deviation from average voltage average voltage

Run the low-voltage leads from the thermostat, through the inlet hole, and into unit low-voltage splice box.

Locate five 18-gage wires leaving control box. These low-voltage connection leads can be identified by the colors red, green, yellow, brown, and white (See Fig. 10). Ensure the leads are long enough to be routed into the low-voltage splice box (located below right side of control box). Stripped yellow wire is located in connection box. Route leads through hole in bottom of control box and make low-voltage connections (See Fig. 10). Secure all cut wires, so that they do not interfere with operation of unit.

TRANSFORMER PROTECTION

The transformer is of the energy-limiting type. It is set to withstand a 30-second overload or shorted secondary condition.

EXAMPLE: Supply voltage is 460-3-60.

AB = 452 v BC = 464 v AC = 455 v

Average Voltage = 452 + 464 + 455 3

= 1371 3

= 457

Determine maximum deviation from average voltage. (AB) 457 452 = 5 v

(BC) 464 457 = 7 v (AC) 457 455 = 2 v

Maximum deviation is 7 v.

Determine percent of voltage imbalance.

% Voltage Imbalance = 100 x		7
	457

= 1.53%

This amount of phase imbalance is satisfactory as it is below the maximum allowable 2%.

IMPORTANT: If the supply voltage phase imbalance is more than 2%, contact your local electric utility company immediately.

C99024

PRE-START-UP

Failure to observe the following warnings could result in serious personal injury:

1.Follow recognized safety practices and wear protective goggles when checking or servicing refrigerant system.

2.Do not operate compressor or provide any electric power to unit unless compressor terminal cover is in place and secured.

3.Do not remove compressor terminal cover until all electri- cal sources are disconnected.

4.Relieve and recover all refrigerant from system before touching or disturbing anything inside terminal box if refrigerant leak is suspected around compressor terminals.

5.Never attempt to repair soldered connection while refrig- erant system is under pressure.

6.Do not use torch to remove any component. System contains oil and refrigerant under pressure. To remove a component, wear protective goggles and proceed as fol- lows:

a.Shut off electrical power to unit.

b.Relieve and reclaim all refrigerant from system using both high- and low-pressure ports.

c.Cut component connecting tubing with tubing cutter and remove component from unit.

d.Carefully unsweat remaining tubing stubs when neces- sary. Oil can ignite when exposed to torch flame.

Proceed as follows to inspect and prepare the unit for initial startup:

1.Remove access panel.

2.Read and follow instructions on all WARNING, CAUTION, and INFORMATION labels attached to, or shipped with, unit.

3.Make the following inspections:

a.Inspect for shipping and handling damages such as broken lines, loose parts, disconnected wires, etc.

b.Inspect for oil at all refrigerant tubing connections and on unit base. Detecting oil generally indicates a refrigerant

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