reaches the set trip level which corresponds to continuous current equal to
ITrip
the output signal
TRIP is activated.
There is also a calculation of the time to trip with the present current. This calculation is only
performed if the final temperature is calculated to be above the operation temperature:
ln
trip
final
trip
n
final
t
ANSIEQUATION1176 V1 EN-US (Equation 139)
The calculated time to trip can be monitored and it is exported from the function as an integer
output TTRIP.
After a trip there can be a lockout to inhibit reconnecting the tripped circuit. The output lockout
signal LOCKOUT is activated when the temperature of the object is above the set lockout release
temperature setting
ResLo
.
The time to lockout release is calculated by the following cooling time calculation.
_
_
ln
final lockout release
lockout release
final n
t
t
æ ö
Q - Q
= - ×
ç ÷
ç ÷
Q -Q
è ø
EQUATION1177 V1 EN-US (Equation 140)
In the above equation, the final temperature is calculated according to equation 134. The
calculated component temperature can be monitored as it is exported from the function as a real
figure, TRESLO.
When the current is so high that it has given a pickup signal PICKUP, the estimated time to trip is
continuously calculated and given as analog output TTRIP. If this calculated time get less than the
setting time Warning, set in minutes, the output WARNING is activated.
In case of trip a pulse with a set duration
tPulse
is activated.
Section 8 1MRK 502 066-UUS B
Current protection
522
Technical manual
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