Caterpillar HV Generator SR-4

Tools needed: 6V-7070 Digital Multimeter 1pc, 12 V DC Battery 1pc

Warning: Do not operate the generator set at more than half of rated speed. Higher speeds, under the conditions of this test can cause damage to the system

Disconnect wires F1 and F2 from the voltage regulator. Disconnect the generator from load

Connect a 12 V DC automotive type battery to wires F1 + and F2 -

Operate the generator set at half the rated speed

Measure and record the AC voltage across the following terminals: T1 and T2

Measure and record the AC voltage across the following terminals: T1 and T3

Measure and record the AC voltage across the following terminals: T2 and T3

Monitor the same voltages as Step 4, while decreasing and then increasing the generator set speed 10%. Do not exceed half of rated speed

- Remove generator outlet box cover. Visually inspect stator output leads

- Visually inspect stator output leads, protective sleeving and insulation for cracking or physical damage. (Same as 7500/9000 hour check)

- Check all exposed electrical connections for tightness

- Check transformers, fuses, capacitors and lightning arrestors for loose mounting or physical damage

- Check all lead wires and electrical connections for proper clearance and spacing

- Check insulation resistance to ground on all generator windings

C. Exciter and PMG stationary fields

Warning: This procedure requires trained personnel with PPE!

Failure of a rectifier suspected?

If a failure of a rectifier is suspected, proceed with the following steps

Rectifier removed from heat sink?

Ohmmeter leads connected across rectifier in one direction?

Ohmmeter leads reversed and connected across rectifier in the other direction?

Meter reading in the other direction

Ground insulation is generally defined as that insulation intended to isolate the current carrying components from the noncurrent bearing components

Support insulation, such as block, slot wedges, etc. are usually made from compressed laminates of fibrous materials, polyester or similar felt pads impregnated with various types of bonding agents

- Inspect for Deterioration Or Degradation Of Insulation From Thermal Aging

Examination of coils reveal general puffiness, swelling into ventilation ducts or a lack of firmness of the insulation, suggesting a loss of bond with consequent separation of the insulation layers from themselves or from the winding conductors or turns

Coil and connection surfaces may be damaged by abrasion or contamination from other sources, such as chemicals or abrasive or conducting substances

Generator Outlet Box Maintenance

Remove generator outlet box cover

Visually inspect stator output leads, protective sleeving and insulation for cracking or physical damage

Check all exposed electrical connections for tightness

Check transformers, fuses, capacitors and lightning arrestors for loose mounting or physical damage

Check all lead wires and electrical connections for proper clearance and spacing

Check insulation resistance to ground on main rotating assembly

Check insulation resistance to ground on main stator assembly