5
IZM63 / IN63 low voltage air circuit breaker
MN013014EN May 2021 www.eaton.com.cn
Section 2: Receiving, handling, and installation
Figure 2-2 Rear view showing current sensor rating
through viewing window
2-6 Adapting cassette
Drawout circuit breaker cassettes are built and shipped in
a “basic” configuration that can be adapted in the field to
mate with specific circuit breakers. Specifically, the rejection
interlock must be configured to the specific circuit breaker
to be mated with the cassette, and the automatic secondary
connections may have to be installed or upgraded. These
operations are described in the following sections.
2-6.1 Rejection interlocks
Within any one physical frame size, the drawout circuit
breakers come in a variety of continuous current and
interruption ratings, some of which are incompatible with
others. Double-wide circuit breakers also come with several
phase sequence options that are also incompatible. To
prevent the insertion of circuit breakers with (1) inadequate
interrupting capability, (2) with physically incompatible
primary disconnects, or (3) with an incompatible phase
sequence, rejection interlock key plates are provided on
both the circuit breaker and the cassette. The key plate
on the circuit breaker is pre-assembled at the factory; but
the cassette-side rejection plate and key pattern must be
assembled and installed by the switchboard builder.
CAUTION
Do not disable rejection interlocks. Doing so and using a
lower capacity circuit breaker in an incompatible cassette
could result in an electrical fault that could result in death,
bodily injury, and/or equipment damage.
Molded rail supports
Extension rail cutout
Figure 2-3 One side of drawout circuit breaker properly
seated on extension rail
The rejection interlocks are steel pins in the floor of the
circuit breaker cassette. As the circuit breaker is pushed
into the structure, the mating pins on the bottom of the
circuit breaker move past a set of corresponding pins in the
cassette if the circuit breaker and cassette are compatible.
If the circuit breaker and the cassette are mismatched, the
rejection pins will block the insertion of the circuit break-
er into the cassette before the levering-in mechanism is
engaged.
Before attempting to push the circuit breaker into the
DISCONNECT position, compare the positioning of rejection
interlock pins in the cassette with the information supplied
on the circuit breaker’s nameplate. Proceed if the circuit
breaker and the cassette are compatible.
2-6.2 Installing secondary jumpers
On drawout and fixed circuit breakers, the automatic
secondary connector between the circuit breaker and the
cassette is coming as a complete set of control circuit
terminals (Terminal blocks and jumpers wires installed);
These parts can be ordered separately and installed by the
customer well. If the necessary connections are not pre-
installed, please contact an Eaton representative. These
kits can also be used to add additional secondary wiring to
upgrade circuit breakers in the field.
