Use these methods to ensure that power panel loads are
balanced.
There are one to three bulk power regulators
(BPRs) for each of the four power cords. Power cords 1 and 2 always
have the same configuration of BPRs, and the same is true for power
cords 3 and 4. Three-phase balance behavior is as follows for each
power cord:
- When three BPRs per power cord are populated, the load
for that power cord is balanced three-phase.
- When two BPRs per power cord are populated, two of
the three-phases draw an equal amount of current and are nominally
57.8% of the current on the third phase.
- When one BPR per power cord is populated, two of three-phases
carry an equal amount of current with no current drawn on the third
phase.
Note: Ground fault interrupt (GFI) circuit breakers are
not recommended for this system because GFI circuit breakers are earth
leakage current sensing circuit breakers and this system is a high
earth leakage current product.
Figure 1. Power-panel
load balancing
The method illustrated in the preceding figure requires that
the connection from the three poles of each breaker to the three-phase
pins of a connector be varied. Some electricians might prefer to maintain
a consistent wiring sequence from the breakers to the connectors.
The following figure shows a way to balance the load without changing
the wiring on the output of any breakers. The three-pole breakers
are alternated with single-pole breakers, so that the three-pole breakers
do not all begin on Phase A.
Figure 2. Power-panel
load balancing
The following figure shows another way of distributing the
unbalanced load evenly. In this case, the three-pole breakers are
alternated with two-pole breakers.
Figure 3. Power-panel
load balancing
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