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WEG Molded Case Circuit Breakers - User’s Manual
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4. tR: the number of seconds required to trip @ 6x. For example, IR - 800 A, - 2 sec
load current - 4800 A (6x). The breaker will trip in 2 seconds.
5. Isd: setting in multiples of IR. For short circuit conditions that exceed the short
delay pick-up setting, the trip unit initiates a trip after a predetermined delay.
6. For the LSI style, the short delay time is a flat response determined by the tsd/
tg switch setting of INST, 120 ms or 300 ms. For the LS style, the short delay
time is an 12t function.
7. Status LED: a green status light indicates the operational status of the trip unit.
If the load current is approximately 20% of the maximum current rating (In) of
the breaker, the status light will blink on and off once each second.
8. Mechanical push-to-trip.
9. The maintenance mode and adjustable INSTantaneous features are only
available on LSI styles. Please refer to the labeling to the left of the test kit
connector. The maintenance mode consists of the two lowest settings of the
INSTswitch: 2.5x and 4.0x. For example, a 1200 A (In) breaker with the switch
set to 2.5x would trip instantaneously when the current exceeded 3000 A.
10. The adjustable INSTantaneous (Ii) Mode has four settings from 6x to 9x.
For example, a 800 A (In) breaker with the (Ii) switch set to 7x would trip
instantaneously with the current at or above 5600 A. The last setting on
the (Ii) switch can be one of three values depending on the frame current:
800 A = 28, 1200 A = 12.
11. On an UBW1200 without maintenance mode, the lowest labeled SDT setting
is labeled INSTaneous. The lowest SDT setting with Maintenance Mode is
labeled as 50ms.
12. The Remote Maintenance Mode is enabled by applying 24 V dc to the two
wire cable that exists the left side of the breaker. The wires are color coded as
follows: Yellow = +24 V and Black = common ground. A blue colored LED, on
the left side of the breaker is the maintenance mode section of the trip unit, will
light. The lighted blue LED indicates that the lowest setting of the maintenance
mode is enabled. This setting corresponds to 2.5x of In. Turning the adjustable
switch on the trip unit has no affect on either the maintenance mode or the INST
mode settings while the blue LED is lit. In addition to the blue colored LED, a
relay contact (C, NO) is available. The wires for this contact exit the left hand side
of the breaker and are color coded as follows: Blue = C, and Red = NO.
