GE GE752 manual Varnish Immersion Treatment After VPI, High±Potential Test, Balancing Armature

GEK±91584D, Vertical Drilling Motor, Type GE752

Minimum Volts	7.3	Varnish Immersion Treatment After VPI
Maximum Volts	8.5	(Armature)
For Magnetic retainers:		The following immersion process must be performed
Minimum Volts	0.7	on the armature assembly after the VPI process.
Maximum Volts	12.4	1. Preheat the armature in an oven at 140￿ C for at
		least five hours.
High±Potential Test		2. The temperature of the armature must not be
		less than 90￿ C, or above 120￿ C, before im-
Frame With Used Coils		mersing. Immerse the armature in a vertical po-
		sition (commutator end up) in the varnish (GE

Apply a high±potential test voltage of 2000 volts, 60

Hz for one minute.

Spec. No. A15B53A) for at least one minute.

Frame With All New Coils

Apply a high±potential test voltage of 3500 volts, 60 Hz for one minute.

Measure leakage current to ground during this test.

5.0 milliamps is maximum.

WARNING: Electric shock can cause serious or fatal injury. To avoid such injury, personnel should take and observe proper precautions during the high±potential testing.

Resistance Measurement

Refer to the DATA section for values and measure the resistance of the exciting and commutating fields.

NOTE: One minute is the minimum time to in- sure adequate varnish penetration.

3.Lift the armature out of the varnish and spin until the excess varnish is removed. Clean the shaft with Xylene (GE Spec. No. D5B9).

4.Bake at 140￿ C in an oven for at least eight hours.

BALANCING ARMATURE

Refer to the appropriate longitudinal section (see Table 2, Page 20, to determine the correct drawing) for balance weight locations. Dynamically balance the ar- mature within 10 grams (0.35 oz.) on the drive end and 12 grams (0.42 oz.) on the commutator end by adding weights on the commutator cap and the armature head.

VARNISH TREATMENT (ARMATURE)

Vacuum Pressure Impregnation (VPI)

After all repairs have been completed, the armature must be vacuum pressure impregnated in GE±702C polyester varnish.

Refer to GEK±101183 for VPI procedure.

Following the VPI processing, the armature must be given a varnish immersion treatment.

NOTE: Do NOT clean previously protected ma- chined surfaces, threads and tapped holes be- fore varnish treating the armature.

REASSEMBLY

Brushholders

1.Using a bolt and washer, attach the brushholder clamp to the frame mount. Position the studs of the brushholder in the clamp, and move the brushholder radially outward as far as possible.

2.Tighten the brushholder clamp bolt but do not torque. Install all brushholders.

3.Connect the brushholder cables. Refer to Table 2, Page 20, to determine the correct connection diagram.

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