Generac 86640 - Manual (Page 18)

Measuring Current
Alternating current measurements can be taken with a
'clamp-on* type ammeter. Amperage should never exceed
the nameplate rating when running the intended electrical
load(s).
Measuring Resistance
Resistance of the main stator windings is very low. Some
meters are not able to read such a low resistance and, for that
reason, use of a very sensitive digital type meter is recom­
mended. A standanj VOM can be used to check for continuity,
shorts or grounded condition.
Effects of Engine Power
The generator engine must provide adequate power to
operate the generator at rated load. The greater the load
current (amperage) or load watts, the greater the engine
power that is needed. As a general rule, approximately 2
engine horsepower is needed for each 1000 watts (1.0 kW)
of generator power.
If the generator’s wattage/amperage capacity is ex­
ceeded, engine power may not be sufficient to handle the
Increased load. The result will be a decrease in engine speed
(rpm) and a corresponding reduction int AC output frequency
and voltage.
A badly worn engine, one that has lost compression, or
one with a mechanical problem may not be able to handle a
load within the generator’s rated capacity. Problems with
generator AC output are often the direct result of an engine
problem, rather than a generator problem.
If engine speed, AC frequency and voltage are normal
when the generator Is running aty no load, but deteriorate
when electrical loads are applied, an underpowered engine
may be the cause of the problem.
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