Heatcraft Refrigeration Products Air-Cooled Condensers none User Manual download pdf (Page 17)

Master/Slave Conguration

The EC motor control signals are wired in a Master/

Slave conguration. This conguration allows for the

maximum sound and energy reduction as well as the

most stable head pressure control. The control signal is

delivered to the master motor (located at the header end

of the unit). The master motor relays the control signal to

the adjacent slave motor. This relay is done until the last

motor is reached. As each slave relays the control signal,

it adjusts the signal so the next slave will run slightly

slower than the upstream motor. The end result of this is

that when a motor receives a small enough signal, it will

turn o. This provides built-in fan cycling.

Protective Features

The EC motors have many built-in protective features.

The EC motors have functions within the motor to

protect against:

• over-temperature of electronics

• over-temperature of motor

• incorrect rotor position detection

With any of these failures, the motor stops electronically

and the alarm relay is switched. With one of these

failures, the motor WILL NOT automatically restart. To

reset, the power supply has to be switched o for a

minimum 20 seconds once the motor is at standstill.

Locked-rotor protection

As soon as the rotor is blocked, the motor gets switched

o electronically and the alarm relay is switched. After

de-blocking, the motor WILL restart automatically.

Under-voltage protection

If power supply voltage falls below ~150VAC/3Ø (for 230V

motors) or ~290VAC/3Ø (for 460V motors) for 5 seconds

minimum, the motor will be switched o electronically

and the alarm relay is switched. If power supply

voltage returns to correct values, the motor WILL restart

automatically.

Phase failure

If 1 phase fails for 5 seconds minimum, the motor will

be switched o electronically and the alarm relay is

switched. If all 3 phases return to correct values, the

motor WILL restart automatically within 10-40 seconds.

EC Motor Wiring

All EC motor wiring is done at the factory. If any motor

wiring needs to be done in the eld, the diagram below

indicates the terminal pin congurations inside the

motor junction box. Terminals in shaded area are not

normally used.

The following diagram shows typical motor wiring for a 1

x 4 EC condenser.

1 2 ... 12 13 14 15 16 17 18 19 20

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Heatcraft Refrigeration Products Air-Cooled Condensers none User Manual Page 17

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