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WEG Molded Case Circuit Breakers - User’s Manual
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1.1. OVERLOAD TRIP
In accordance with standards requirements, the trip unit initiates a trip of the circuit breaker
within two hours of an overload of 135 percent, and a trip in less time for higher overloads.
A “Thermal Memory” effect prevents the breaker from being reenergized immediately
after an overload. A “cooling off” period of up to 5 minutes is required, which allows time
for the cabling to cool off.
1.2. SHORT DELAY/INSTANTANEOUS TRIP
For short circuit conditions that exceed the short delay pick-up settings, the trip units
initiate a trip after a delay prescribed by the I²t ramp function for trip units designated LS
and SG. A flat response time delay action is provided by trip units designated LSI and
LSIG unless the instantaneous (I) setting is selected.
1.3. DC APPLICATION
310+ trip units are suitable for AC application only.
1.4. FIELD TESTING
Test port is available for functional filed testing of the trip unit when connected to test kit.
1.5. INTERNAL ACCESSORIES
Internal accessories mount in the breaker.
Notes: Shunt trip and undervoltage accessories, if required, must be mounted in the left pole.
Digitrip 310+ trip unit versions with ground fault protection are supplied with an auxiliary switch, mounted
in the right pole of the trip unit.
This instruction leaflet gives procedures for instalattion and field testing on
UBW1200 circuit breakers and describes the different trip unit characteristics. For
this publication, the term circuit breaker shall also include the molded case switch.
2. INSTALLATION
The installation procedure consists of inspecting the circuit breaker, installing
the accessories and terminals and, if required, mounting the circuit breaker,
connecting the line and load conductors and accessory wiring, and adjusting trip
settings. Circuit breakers, accessories, and terminals may be supplied in separate
packages. To install the circuit breaker, perform the following steps.
2.1. INSPECTION
Make sure the circuit breaker is suitable for the intended installation by comparing
nameplate date with existing equipment ratings and system requirements. Inspect
the circuit breaker for completeness and check for damage before mounting.
