Eaton NRX Instruction Manual - page 26
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Section 4: Circuit breaker features and accessories
Series NRX with PXR - type RF low voltage power (air) circuit breakers instruction manual MN013002ENH03 September 2016 www.eaton.com
Shunt trip (ST)
The shunt trip opens the circuit breaker instantaneously
when its coil is energized by a voltage input.
Undervoltage release (UVR)
The undervoltage release opens the circuit breaker when
its supply voltage falls into the range of 35 – 60% of rated
voltage. If the release is not energized to 85% of its supply
voltage, the breaker cannot be closed electrically or
manually.
Overcurrent trip switch (OTS)
An overcurrent trip switch (bell alarm) provides an electrical
indication when a circuit breaker trips as a result of the trip
unit. Opening as a result of a circuit breaker’s manual open
button, shunt trip, or undervoltage release does not cause
the overcurrent trip switch to operate. Overcurrent trip
switches are available in two switch combinations only.
Auxiliary switch
An auxiliary switch provides remote electrical indication if
the circuit breaker is open or closed. Each switch has one
normally open (“a” contacts with the same state as the
breaker contacts) and one normally closed (“b” contacts
with the opposite state of the breaker contacts) type con-
tact. Auxiliary switches are available in two switch combina-
tions only.
Other internal electrical devices
Internally mounted electrical devices which do not utilize the
accessory trays include:
●
Spring release;
●
Latch check switch; and
●
Motor operator.
Spring release (SR)
The spring release (closing coil) remotely closes the circuit
breaker when the coil is energized by a voltage input. The
spring release activates momentarily when voltage is first
applied, and voltage must be removed in order to reset the
spring release to activate again. When the spring release
is used in conjunction with a Spring Release Latch Check
switch and voltage is maintained to the spring release,
activation of the spring release is delayed until the closing
spring is fully charged and the trip latch is reset (not held in
the tripped position). After these conditions are met and the
spring release has activated, voltage must be removed to
reset the spring release to activate again.
Latch check switch (LCS)
A latch check switch (LCS) indicates when the circuit break-
er is “ready to close” (charged and not held tripped). Two
versions of the LCS are available:
1.
The “spring release LCS”, wired directly to the spring
release, will not permit activation of the spring release
until the circuit breaker is fully charged and the trip latch
is reset.
17. The LCS for Remote Indication consists of one Form C
contact wired to the circuit breaker secondary contacts
for integration into external control schemes.
ote:
N
Wiring the LCS for remote indication directly in series
with the SR accessory is not recommended as this
will override the electrical “anti-pump” feature of the
spring release.
Motor Operator
A motor operator is an electric motor assembly internally
mounted in the circuit breaker. It charges the closing
springs electrically for remote or local operation. The motor
operator can be factory or field installed.
Mechanical devices
The following are optional mechanical type accessories:
●
Pop-out trip indicator, non-interlocked and interlocked;
●
Operations counter;
●
Off key lock;
●
Pushbutton cover;
●
Prevent close cover;
●
Lockout cover;
●
Cassette safety shutters;
●
Door escutcheon;
●
IP55 resistant cover; and
●
Mechanical interlock.
Non-interlocked pop-out mechanical trip indicator
A non-interlocking red mechanical trip indicator, located to
the right of the trip unit on the breaker’s front faceplate
(Figure 5), operates by releasing and popping out any time
the breaker trips due to an overcurrent condition. It will not
prevent the breaker from being reclosed. The indicator is
reset manually by pushing it back in.
An optional overcurrent trip switch (bell alarm) can be used
in conjunction with the mechanical trip indicator. The over-
current trip switch operates off the position of the mechani-
cal trip indicator, and is reset when the indicator is reset.