Workshop Damage Report

A damage report of one of our assignments can be found below as an example. We would like to show you what exactly happens with your generators and motors, so that you can be confident to receive the best possible service.

Damage Report

Manufacturer: AvK
Type: DIG 130 i / 4
Number: 8325522 C103
Voltage regulator: Cosimat N+ / QPF / CUN1
Power: 6,300 V; 2.067 kVA; 189A; 1,500 rpm; 7,000kg

The generator was delivered to our workshop, where it was dismantled and analysed. The generator was delivered with the corresponding coupling elements.

Insulation resistances

Stator winding test voltage: 5,000 VDC

U – PE : 13.77 G
V – PE : 13.09 G
W – PE : 11.72 G
U – V : 21.4 G
V – W : 22.5 G
U – W : 25.4 G

Rotor winding test voltage: 500 V DC > 200.00 MΩ

Exciter winding test voltage: 500 V DC > 200.00 MΩ

Auxiliary winding test voltage: 500 V DC > 200.00 MΩ

Polarisation index: 3.79

Despite the significant contamination of the generator, the insulation resistances were normal.

Photos Documenting the Repair

Generator when delivered

The protective grilles were missing.

Generator im angelieferten Zustand

Check whether they are still at the site.


Non-drive end ventilation covers removed, view of rotating rectifier, terminal strip and transformers.

Rotating rectifier


Regulator terminal strip

Regulators N+ / QPF / CUN1

Detailed view of a regulator / QPF

Main terminal box

It can already be seen that the generator is in a dirty and very poor general condition. Attempts should be made to optimise the air intake / conditions at the site or to shorten the maintenance intervals.

Disassembly (non-drive end)

View into the stator

Exciter stator

Loose and damaged bandages

Exciter rotor

Roller bearings

End shield; fit in the shield heavily shrunk

The fit in the end shield displays a clearance of +0.07 mm and must be fitted with a sleeve. The clearance of 0.02 mm for the shaft is o.k.



Fitting of the bearing plate

Wave A-Side

Detailpicture winding

The fit in the end shield displays a clearance of +0.08 mm and must be fitted with a sleeve. The clearance of 0.03 mm for the shaft is o.k.


A few transformers became detached due to the vibration

They will have to be refixed after the overhaul/cleaning.

The connection threads on the voltage transformer 8.43.006-2300 for measurement and electrical isolation were totally worn, presumably due to overtightening. The voltage transformer must be replaced.

The generator must be washed several times, since even the air channels are clogged with dirt. Then the generator was to be dried in the kiln. Subsequently, the slot liners were checked for sufficient strength.

Im Anschluss werden die Deckschieber (Nutenverschlussteile) auf Festigkeit geprüft.

The coupling Reich Arcusafelx ACH11SN

The coupling was to be replaced / provided by the customer.

The diodes and varistors were also to be replaced.

All wound parts were washed, dried in the kiln and subsequently preserved. The rotor was fine-balanced, and both the terminal box and all terminals in the main terminal box were examined and checked for insulation damage. The functions of the regulator can only be tested on the test bench.