power carrying conductor (hot wire)
that each phase receives exactly the
and the neutral (ground) wire or among
In practically all TO
several power carrying wires.
loading will exist among the different
a. Phase loading.
When a load is
phases, However, the loadings on the
connected between a hot wire and a
neutral wire the power is assumed to
possible, and at the very least,
be supplied completely by the hot
within 10 percent, for the reasons
Likewise, a load connected
stated in b above.
Thus the total
between two or more hot wires is
power delivered by the generator in
distributed equally among the hot
the maximum loaded phase must be less
Many loads may be connected
than or equal to 1.1 times the power
among various hot wires in a given
delivered in the minimum loaded phase.
For example, in
Although this amount of unbalance is
within acceptable limits, it is still
an installation fed by a 3 4W
considered a relatively high degree of
generator, single phase loads may be
unbalance in a system, the greater the
throughout the system.
chances of causing the bad effects
matter how many loadings are supplied,
An attempt should
or in what arrangement they may be,
the generator responds to the total
generator within 1 percent, so that
load on each of its phases and
the power delivered in the maximum
attempts to supply the required power
loaded phase is less than or equal to
to satisfy the particular load in each
1.01 times the power delivered in the
minimum loaded phase.
of this objective is often a tedious
b. Phase balance. It is imperative
trial and error procedure, but it is
that the power in each phase just as
not impossible, and it becomes less
it leaves the generator be balanced;
that is, each phase receive the same
This will only come about as a result
of having equal total loadings on each
of the phases, and the layout must be
designed to achieve this.
BALANCING SINGLE-PHASE SYSTEMS
loading has the following three bad
A 1 2W system is the basic load
impossible to get full output out of a
unbalanced since there are only two
wires, which can only be connected to
overloading the others.
The 1 3W 120/240V
one load group.
system, however, contains two hot
(2) Voltage regulation.
wires and a neutral which means that
two single phase 120V load groups
unbalancing causes high voltage on the
and/or one single phase 240V load
lightly loaded phase and low voltage
group may be served.
on the others.
such a system, the two single phase
approximately equal size.
will damage generating equipment.
BALANCING THREE-PHASE SYSTEMS
c. System balance.
In practice it
is highly improbable that it will be
A 3 3W 208V system contains three hot
wires, meaning that three single-phase
loadings in an actual installation so