Generator Faults
9.2.16
Kapitel/Chapter 8: Generator Faults - Seite/Page 145
8.7.6 Measuring the inductive resistance
An Ohm measurement of a winding does not always give reliable information concerning the state of the winding. If
there are resistance irregularities between the windings parts, this is a sure sign that the winding is defective. This
means the opposite cannot be concluded. This means a winding can also be defective, if the resistance values
between the windings parts do not show great deviation.
Measurement of the inductive resistance gives a better reading. A Special measuring device is necessary for this.
The inductively is measured in the same manner as the resistance, i.e. the windings parts are compared. The value
of the inductive resistance is given in mH (milli Henry).
Note: The values are greatly dependent upon the measuring method (type of ohmmeter).
8.8
Generator provides no voltage
8.8.1 Rotor magnetism loss and „re-magnetising“
ATTENTION!
See “Safety Instructions - Safety First!” on Page 15.
In the case of asynchronous generators, the generator cannot independently increase voltage after standing still, or,
if it is switched off under full load. This is because the rotor has lost its remaining magnetism.
This remaining magnetism can be restored simply by use of a DC battery. In addition the „shore power“ must be
switched off and any connection to an AC-source must be interrupted.
Likewise the generator must be switched off, i.e. also the starter may not be operated. The power source selector is
switched to „generator“. Only the plug socket must be connected with the generator.
Now the two poles of a 9 Volt battery are connected to the plug socket or held against the appropriate contacts of the
on-board current distributor. Do not use a battery bank or the generator starter battery, this could damage the
winding. The DC voltage only may be applied for a short time (1-2 seconds). In the winding the remaining
magnetism is restored by a short current pulse, and the generator can normally be started.