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4. Panel design and equipment
4.7 Ith Limiters
Additional safety feature on the top of each panel.
It consists of miniature microswitch embedded in
the steel housing, generates an immediate trip
signal when overpressure flap is opening.
Reaction time depends on energy of internal arc
and distance from the flap. Reaction time is less
than 15 ms. The signal from the Ith limiter can be
sent directly to trigger circuit-breaker OFF.
Install the Ith limiters on the top of the panel
frame. Install the lever on overpressure relieve
flap and turn the limiter on. Tighten both bolts.
Flap and Lever should be aligned with Ith limiter’s
body.
The lever is made of spring steel and allows to
test the function of the limiter by springing it.
After releasing, the lever must return and the
limiter will turn on.
Figure 28: Ith limiters installed on right side of the
switchgear panel
1 Ith limiter
2 Pressure relief flap
1 Ith limiter
2 Pressure relief flap
Figure 29: Ith limiters installed on right side of the
switchgear panel
Figure 30: Valid for microswitch of type LXW37
Figure 31: Valid for microswitch of type M1S 6610
Figure 32: Valid for microswitch of type Crouzet
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