3000 Frame SR5 Electric Power Generation Caterpillar

Illustration 1	g01388839
PMPE Generator Wiring Diagram for 3000 Frame Family (CR1-C6) Diodes (CR7) Varistor (L1) Exciter stator (L2) Exciter rotor (L3) Main rotor (L4) Main stator (L5) PMG stator (PM) Permanent magnet (RFA) Rotating field assembly (CT1) Optional voltage droop transformer (T0, T1, T2, T3, T7, T8, T9) Generator terminals

Measure the resistance of the following windings: (L1), (L2), (L3), (L4) and (L5). The winding that is being tested must be disconnected from the other components before the resistance can be measured.

Note: The winding temperature affects the resistance. When the winding temperature increases, the winding resistance increases. When the winding temperature decreases, the winding resistance decreases. Resistance values in technical marketing information (TMI) are based on 20° C (68° F) ambient conditions. Measured resistance must be corrected to the nominal 20° C (68° F) temperature for comparison. Other references such as rewind manuals may show resistances at other ambient temperatures like 25° C (77° F).

Resistance

For the resistance checks, use a micro ohmmeter such as Wheatstone bridge or a Kelvin bridge. Most digital multi meters and analog multi meters are not accurate enough to measure the coil resistance. The resistance values are correct only at the given temperature. If the winding temperatures are different from the temperatures in the table, use the following formula in order to find the actual resistance.

Illustration 2	g03434270

The following resistance measurements are approximations. If the measured value is not near the listed approximation, the winding is probably damaged. For a more precise resistance value, consult the Technical Marketing Information (TMI). Refer to the generator arrangement that is in question.

The following windings have little resistance: (L2), (L4) and (L5). The resistance of these windings will measure near 0 ohms. Use a Digital Low Resistance Ohm (DLRO) meter or a micro-ohmmeter to measure the resistance of the windings.

Exciter Rotor (L2) - Refer to Table 2.

Main Stator (L4) - less than 0.1 ohm

Pilot Exciter Stator (L5) - less than 0.87 ohm

Use a DLRO in order to measure the resistance of field windings (L1) and (L3).

Exciter Field (Stator) (L1) - Refer to Table 2.

Main Field (Rotor) (L3) - approximately 0.84 ohms to 1.4 ohms

Note: There should be no continuity between any winding and ground. There should be no continuity between any winding and another winding.

Note: Refer to the technical marketing information (TMI), that is located at the Caterpillar web site "TMI.cat.com". The TMI contains the most up-to-date generator specifications.