Caterpillar — Generator Set Functional Test
Testing & diagnosis
From a Caterpillar owner's manual covering: 3306B, 3406, 3406E, 3412C, SR4B. Check it applies to your exact model before use.
Applies to: Caterpillar 3306B, Caterpillar 3406, Caterpillar 3406E, Caterpillar 3412C, Caterpillar SR4B
Before you start
- Do not operate the generator set at a speed higher than one-half of the rated speed.
Procedure
- Stop the generator. Connect the potential transformer's high voltage winding to generator terminals T1 and T2. Connect the voltmeter to the low voltage winding.
- Disconnect wires F1+ and F2- from the voltage regulator. Disconnect the generator from the load.
- Connect a 12 VDC automotive battery to wires F1+ and F2-.
- Operate the generator set at half the rated speed.
- Measure the AC voltage across the low voltage terminals corresponding to T1-T2, T2-T3, and T3-T1. Record the voltages.
- Monitor the voltage between any two locations, then decrease the generator set speed by 10 percent and increase it by 10 percent.
- The measured voltages should be nearly equal and should measure a minimum of 85 VAC.
- When speed is decreased by 10 percent the voltages should decrease by 10 percent; when increased by 10 percent the voltages should increase by 10 percent.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Minimum 85 VAC
Full service-parts list: Caterpillar 3406 →, Caterpillar 3406E →, Caterpillar 3412C →, Caterpillar SR4B →
Source: Caterpillar owner's manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.