Generator Set Start Module (AC Input) Caterpillar

• 236-4955 Single Unit 480 VAC 60 Hz

• 236-4956 Dual Unit 480 VAC 60 Hz

• 236-4957 Single Unit 400 VAC 50 Hz

• 236-4958 Dual Unit 400 VAC 50 Hz

Illustration 1	g00941021
Simplified Circuit Diagram for the Generator Set Start Module

The Generator Set Start Module receives three-phase AC voltage from a reliable power source such as a UPS. The Generator Set Start Module converts the AC voltage into 24 VDC for the starter motor. Unlike batteries, the Generator Set Start Module will indicate the functional status by the state of the Customer Status Contacts. The relay contains a set of normally open contacts that are used in order to indicate if the module is in normal operating status. When the contact is energized, the normally open contacts close. Specifically, the relay is energized whenever the following conditions are true:

• AC power is applied to the module.

• The input breaker is closed.

• The thermal switches are closed.

• All internal fuses are good.

Illustration 2	g00990184
Simplified Circuit Diagram for the Interconnection of 2 Generator Set Start Modules

For 3516 applications, a Dual Generator Set Start Module configuration is required in order to make sure that each starter receives the momentary starting cranking amps that is required.

The Generator Set Start Module is capable of being configured on-site for lower voltages that better match the application.

The Generator Set Start Module provides redundant starting capability for the Caterpillar generator set. This option increases the generator's starting reliability. The Generator Set Start Module should be used as a redundant starting option to batteries.

The Generator Set Start Module can be mounted on the floor or on a wall. In either installation, the module should be securely fastened in order to support the loads of the Generator Set Start Module.

Internal Components and Internal Connections of the Cabinet

Illustration 3	g00975832
(90) Customer Status Contacts (91) 380 VAC to 480 VAC Three-Phase Input Voltage (92) + DC Input (93) + DC Output (94) - DC Output (95) - DC Input

Illustration 3 identifies some of the components and connections that are found inside the cabinet of the Generator Set Start Module.

Operational Description

Illustration 4	g01078767

1. On the Generator Set Start Module, close "CB1" (50). Once "CB1" (50) is closed, the normally open "AUX" contact that is associated with "CB1" (50) also closes.

2. The primary winding of "T2" (48) receives voltage from the following phases: a and b. This voltage passes through the following components before reaching the primary winding of the transformer "T2": "F1" (47) and "F2" (47)

3. The secondary winding of "T2" (48) is 230 VAC. This voltage is fed to "K1" (46) via two temperature sensors that are normally closed. One temperature sensor is used to monitor the overtemperature of "T1" (54). The second temperature sensor is used for monitoring the overtemperature of the diode at the heat sink.

4. The contactor "K1" (46) closes. The normally open auxiliary contact of the contactor also closes. When the normally open auxiliary contact of the contactor closes, "CR1" (44) becomes energized. The "K1" relay (46) provides Customer Status Contacts in order to monitor the status of the device.

5. Once contactor "K1" (46) is closed, voltage is supplied to the primary winding of "T1" (54). "T1" (54) steps down the voltage to 24 VAC. A three-phase bridge rectifier converts Alternating Current (AC) into Direct Current (DC).

6. The following components are used to filter the voltage: capacitor "C1" , capacitor "C2", 2 resistors, fuse "F3" (44) and "F4" (44).

7. If "F3" (44) or "F4" (44) opens, a 24 volt potential is created across the fuses. This voltage energizes "CR2" or "CR3". In addition, circuit breaker "CB1" (50) trips. The Generator Set Start Module becomes de-energized. When the "F3" (44) or "F4" fuses open, the relay for the Customer Status Contacts is de-energized.

8. If "F1" (46) or "F2" (46) opens, "T2" (47) is de-energized. Contactor "K1" (46) opens. When this occurs, the module does not supply DC power. Contactor "K1" (46) will not be energized, and a change is forced in the status of the Customer Status Contacts.