086345-504 ABB Controller module motor card inventory

Description

The overload protection function must not trip the circuit-breaker in 2 hours
for current values which are lower than 1.05 times the set current, and must
trip within 2 hours for current values which are lower than 1.3 times the set
current.
By “cold trip conditions” it is meant that the overload occurs when the circuitbreaker has not reached the normal working temperature (no current flows
through the circuit-breaker before the anomalous condition occurs); on the
contrary “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.
The following pages show some examples reporting the settings of thermomagnetic releases.
To simplify the reading of these examples, the tolerance of the protection functions has not been considered.
For a proper setting it is necessary to consider the tolerances referred to the
type of thermomagnetic release used; for these information please refer to the
technical catalogues.