The document discusses checking pole connectors in machines containing salient poles to verify tight electric contact. Over time, poor contacts between field windings can develop due to loose bolts, corrosion, or material changes. This causes heating and potential arcing, damaging machine components. To check connectors, an adjustable DC source energizes the series pole windings, and the voltage drop across connectors is measured. High readings or excessive temperature indicate poor connectors. Properly checking requires a DC source and safety precautions during voltage application and cooling.

1. CHECK OF POLE CONNECTORS
General:
The check of the pole connectors (i.e. the electric connection from field winding of one pole to the
field winding of the next pole) is done in order to verify the tight electric contact of these connectors.
Introduction
During long-time service of machines containing salient poles, the electric contact between the field
windings may become poor. Reasons for this are e.g. loosening of the bolts, corrosion of contact,
surfaces, settings in contact materials etc. In consequences, in service such poor contacts are
heated up by the field current and – as the worst – arcing is caused, followed by severe destruction
of machine components.
Checking Technique
During the check of pole connectors, the series connection of all pole windings is enegized by an
adjustable DC source I~ through the field-windings and thus over the pole connectors. I~ should be
chosen in a magnitude near to the nominal exciter current of the magnet wheel. While the magnet
wheel is energized, both the voltage drop (mV) at the pole connectors are recorded (Figure 1 and 2).
High mV-readings and excessive temperature rises obviosly indicate poor pole connectors.
General Requirements
For the performance of the check of pole connectors an appropriate DC source is the minimum
requirement. During the application of the DC voltage, safety precautions and the cooling conditions
have to be observed.
© This QM-Instruction is properly of PNG Power and must neither be copied nor used in any other
way without the written consent of PNG Power. Neither is it to be handed over nor in other way
communicated to a third party. Infringement will lead to prosecution.
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