Introducing Froment Load Banks
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When is non unity power factor testing required?
This depends on the type of test that is required.
Sometimes, for smaller generators where a standardised alternator design is in use, the
electrical performance of the alternator and control gear can be assumed to be adequate.
In this case the only requirement during testing is to prove that the motive source of
the generating set is capable of operating at full power without overheating and a purely
resistive load is all that is required. This is sometimes referred to as active load (power
factor 1.0) or unity power factor.
However, in many situations the electrical performance of a generating set is of critical
importance. In these cases it is necessary to put the motive source, alternator and its
associated control gear all under stress during testing. To do this a combined load made
up of resistive and reactive elements is required.
Combined loads are also required to set up systems where multiple generating sets are
running in parallel or where it is necessary to simulate the start up of a large motor.
Multiple generator testing
Multiple generating sets running in parallel can present a problem for installers when it
comes to setting up load sharing and voltage regulation on a new system. A purely resistive
load will not provide the required load characteristics and a combined load is required for
initial calibration and testing.
What equipment is required?
Combined load testing can be accomplished by using a combined load bank (a load bank
consisting of a mixture of resistive and reactive load elements) or by running two or more
different type load banks in parallel.
The exact combination of equipment required will depend on the specific application.
Typically power factors from 1.0 to 0.7 are used but motor start simulation may require
a power factor as low as 0.4. See the appendices of this manual for more details of the
calculations involved.
Note: Froment com-
bined, inductive and
capacitive load banks
are in the 6000 S
ERIES
range. Froment purely
resistive load banks
are in the 3000 S
ERIES
range and Froment con-
tainerised units are in
the 8000 S
ERIES
range.
