GE Industrial Solutions GE ZENITH SERIES MDU - Manual (Page 42)

Special Instructions
GE Z ENITH C ONTROLS
MDU Owner’s Manual
601 S HILOH R OAD January 2013
Plano, TX 75074 Page 42
8.0 Special Instructions
8.1. Output Panel boards
MDUs that are supplied with output panel boards should have all the output loads balanced at the
panel boards. The objective is to place equivalent current wave forms and magnitude on each
output. With most (3) three phase loads containing a full wave bridge rectifier, distributing the 3 pole
breakers (by ampacity) evenly across matched Panel boards provides optimum balancing. Duty
cycle, if available, should also be considered. Single phase loads with high third harmonics should
also be evenly balanced across the Panel boards. Below are the steps to follow for proper balancing
of circuits.
A. Divide all output into (3) three categories by breaker pole position (1 pole, 2 pole, 3 pole).
B. Subdivide the 3 categories by breaker size (ampacity).
C. Assign the largest 3 pole breaker to panel board #1.
D. If there is an even number of the larger 3 pole breakers, assign them evenly between the panel
boards. If you are unable to assign them evenly, then assign smaller 3 pole breakers to the
panel having fewer breakers.
E. Perform steps c) and d) in regards to the next size down, 3 pole breakers. Continue with this
procedure until all 3 pole breakers are installed.
F. Repeat this process with all 2 pole and 1 pole breakers respectively. Units that are equipped
with four (4) or six (6) Panel boards should first divide the circuits into groups of two (for 4 Panel
boards) and groups of three (for 6 Panel boards). Once the circuits are evenly divided, proceed
with the above steps.
Note: Do not assign only single pole or two pole breakers to an individual panel board.
8.1.1. Panel board manufacturers
When choosing the proper distribution breakers for use on a specific panel board within
your MDU, be sure to use only distribution breakers that are compatible with associated
panel board. Below is a list of compatible distribution breakers for specific Panel boards. If
you need any assistance in choosing the proper breakers please contact GE’s field support
division at (800) 637-1738.
1. General Electric Panel boards: Use only General Electric (type AQL3422AT) type THQB,
THHQB, TXQB, or THQL breakers.
If another brand panel board not mentioned above is placed in your MDU, then be sure and
only use a distribution breaker that is compatible with that manufacturer. You may need to
contact the panel board manufacturer to ensure compatibility.