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CAUTION: When servicing the HIGH VOLTAGE section of the dryer, the ELECTRIC
SERVICE MUST BE DISABLED.
THE "EMERGENCY STOP" (E-Stop)
BUTTON DOES NOT DISABLE THE HIGH VOLTAGE TO THE DRYER.
1. Control/Electrical System Description
a. 3-Phase (3ø) Electrical Power
The 3-phase (3ø) electrical power for the dryer enters the dryer through the power distribution block
located in the dryer base electrical box. It is then distributed to the blower (impellor/fan) motor, drive
(tumbler/basket) motor, and transfer circuits.
1) Blower (squirrel cage fan) Motor
The Blower (squirrel cage fan) Motor circuit consists of a blower motor thermal magnetic overload.
The overload current is adjustable by a dial located on the face of the overload. (Refer to the electrical
specification diagram for correct current setting.)
Attached to the thermal magnetic starter is an auxiliary contact used to sense an overload trip. This
produces a safety error so the dryer service is disabled (the dryer will not start).
In series with the thermal magnetic overload is the blower motor contactor. This device enables the
supply voltage to reach the blower (squirrel cage fan) motor. The blower motor contactor is controlled
by the Phase 5 microprocessor controller (computer). (Refer to Section b-1 on page 84 for micro-
processor [computer] information.) When 24 VAC is applied to coil A1-A2, the contactor closes and
enables the circuit.
The blower (squirrel cage fan) motor used for gas model and for steam model dryers is 25 HP (horse-
power). The motor wiring configuration is dependent on the specific voltage of the dryer. When
wiring the motor, refer to the motor nameplate.
2) Drive (tumbler and basket) Motor
The Drive (tumbler and basket) Motor is supplied by the 3-phase (3ø) power source entering the drive
motor thermal magnetic overload. The overload current is adjustable by a dial located on the face of
the overload. (Refer to the electrical specification diagram for correct current setting.) In this circuit,
the drive motor contactor follows the thermal magnetic overload.
The drive motor has two (2) separate sets of coils and two (2) separate sets of contacts. One (1) of
these sets is for forward tumbler (basket and drum) rotation and the other for reverse tumbler (basket
and drum) rotation. The thermal magnetic overloads and the contactors are located in the left hand
electrical cabinet. The direction of the drive motor is determined by the phases going into the motor
(i.e., in a reverse direction phase, L1 and L2 are switched). When viewing this contactor (from the
front of the dryer), the left hand block connections are for the forward rotation direction (clockwise
[CW]).
The drive (tumbler and basket) motor is a 7-1/2 HP (horsepower) motor. Refer to the motor nameplate
for specific terminal box wiring.