PFTL101A 2.0KN PFTL101B 2.0KN ABB Spare parts for tension sensor amplifier

PFTL101A 2.0KN PFTL101B 2.0KN ABB Spare parts for tension sensor amplifier

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The overload protection function must not trip the breaker in 2 hours for current

values which are lower than 1.05 times the set current, and must trip within 1.3

times the set current. By “cold trip conditions”, it is meant that the overload

occurs when the circuit-breaker has not reached normal working temperature

(no current flows through the circuit-breaker before the anomalous condition

occurs); on the contrary by “hot trip conditions” refers to the circuit-breaker

having reached the normal working temperature with the rated current flowing

through, before the overload current occurs. For this reason “cold trip conditions”

times are always greater than “hot trip conditions” times.

The protection function against short-circuit is represented in the time-current

curve by a vertical line, corresponding to the rated value of the trip threshold I3.

In accordance with the Standard IEC 60947-2, the real value of this threshold

is within the range 0.8·I3 and 1.2·I3. The trip time of this protection varies

according to the electrical characteristics of the fault and the presence of other

devices: it is not possible to represent the envelope of all the possible situations

in a sufficiently clear way in this curve; therefore it is better to use a single

straight line, parallel to the current axis. All the information relevant to this trip

area and useful for the sizing and coordination of the plant are represented in

the limitation curve and in the curves for the specific let-through energy of the

circuit-breaker under short-circuit conditions.

Consider a circuit-breaker type T1 160 In 160 and select, using the trimmer for

thermal regulation, the current threshold, for example at 144 A; the magnetic

trip threshold, fixed at 10·ln, is equal to 1600 A.

Note that, according to the conditions under which the overload occurs, that is

either with the circuit-breaker at full working temperature or not, the trip of the

thermal release varies considerably. For example, for an overload current of

600 A, the trip time is between 1.2 and 3.8 s for hot trip, and between 3.8 and

14.8 s for cold trip.

For fault current values higher than 1600 A, the circuit-breaker trips

instantaneously through magnetic protection.