Electrical system – 5000

10.8.2 Transistor regulator

General

The ZAPI SEM-X transistor regulator drives the traction motor. It controls the speed by varying the rotor voltage using pulse width modulation (PWM). This also includes varying the “ON” time of the MOS transistors used to regulate rotor current.

Changing the truck’s travel direction is achieved by reversing the polarity in the field winding (F1-F2). The regulator features a transistorised four-quadrant bridge and a single-quadrant bridge for the rotor winding. A status LED (Fig. 10 AL) displays eventual error conditions which may be present.

Fig. 10 B shows the connector for the hand terminal.

NOTE!

In order to see the alarm status LED or gain access to the connector for the hand terminal it is necessary to fold out the main electrical panel. See “10.4 Accessing main electrical panel” on page 6.

Safety

The regulator is a high-power component. When working on a battery operated vehicle, necessary precautions should be taken. This includes, but is not limited to, correct training, use of eye protectors, avoiding use of lose-fitting clothes, removal of watches and jewellery, and use of insulated tools only.

WARNING!

Risk of short-circuiting. Remove all watches, jewellery and always use insulated tools only.