NORDAC LINK (SK 155E-FDS / SK 175E-FDS) – Users Manual for Motor Starters as Field Distributors
106 BU 0155 en-3520
8.2 Operation on the FI circuit breaker
Leakage current of ≤ 20 mA is expected during operation of the motor starter. It is suitable for
operation on the FI circuit breakers for the protection of persons.
8.3 Trigger classes (I²t)
The devices support the following trigger classes according to product standard IEC 60947-4-2:
• 5
• 10A
• 10 (only for motors with rated current ≤ 4.0 A
The I²t-trigger classes also take into account the loads which occur under normal operation (less than
110 %). Because of this, the switch-off times differentiate between a motor which has been in
operation for some time ("warm") motor and a "cold" motor which has just been started.
In addition, the trigger characteristic curves are subject to tolerances due to the relatively large
measurement range.
The FI switches off immediately above an output current of 56 A. If the output current exceeds 9x the
value of the rated motor current, switch-off is additionally accelerated (kink in the characteristic
curves).
This results in the following characteristic curves:
Outline conditions
• Typical for ambient temperature 20°C,
• Tolerance range, incl. temperature influences,
• Immediate triggering for I > 56 A,
• Class 10 only for I
nenn
≤ 4 A
Legend
– A: Response time
– B: Overcurrent factor I/I
nenn
(I
nenn
= parameterised rated current)
Figure 4: Trigger class curves
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