American Dryer Corp ML-310 Phase 7 Button does not Disable the High Voltage to the Dryer

CAUTION: When servicing the HIGH VOLTAGE section of the dryer, the ELECTRICAL POWER 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 (basket [tumbler]) 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 7 microprocessor controller (computer). (Refer to Section b-1on page 78 for microprocessor controller [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 dryers is 15 HP (11.18 kw) and for steam model dryers is 25 HP (18.64 kw). The motor wiring configuration is dependent on the specific voltage of the dryer. When wiring the motor, refer to the motor nameplate.

2)Drive (basket [tumbler]) Motor

The drive (basket [tumbler]) motor converts 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 basket (tumbler) and drum rotation and the other for reverse basket (tumbler) 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, the left hand block connections are for the forward rotation direction (clockwise [CW]) when viewed from the front of the dryer.

The drive (basket [tumbler]) motor is a 5 HP (3.73 kw) motor. Refer to the motor nameplate for specific terminal box wiring.

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