ABB REL650 Technical Manual page 242

Section 7
Current protection
236
value. The calculated component temperature is available as a real figure signal,
TEMP.
When the component temperature reaches the set alarm level AlarmTemp the
output signal ALARM is set. When the component temperature reaches the set trip
level TripTemp the output signal TRIP is set.
There is also a calculation of the present time to operate with the present current.
This calculation is only performed if the final temperature is calculated to be above
the operation temperature:
æ
Q
t
= - × ç final
t ln
ç
operate
Q
è
final
EQUATION1169 V1 EN-US
The calculated time to trip is available as a real figure signal, TTRIP.
After a trip, caused by the thermal overload protection, there can be a lockout to
reconnect the tripped circuit. The output lockout signal LOCKOUT is activated
when the device temperature is above the set lockout release temperature setting
ReclTemp.
The time to lockout release is calculated by the following cooling time calculation.
The thermal content of the function can be reset with input RESET.
æ
t
= - × ç
t ln
ç
lockout release _
è
EQUATION1170 V1 EN-US
In the above equation, the final temperature is equal to the set or measured ambient
temperature. The calculated time to reset of lockout is available as a real figure
signal, TENRECL. This signal is enabled when the LOCKOUT output is activated.
In some applications the measured current can involve a number of parallel lines.
This is often used where one bay connects several parallel cables. By setting the
parameter IMult to the number of parallel lines (cables) the actual current on one
line is used in the protection algorithm by dividing the measured current by the
total number of cables. To activate this option the input ENMULT must be
activated.
The protection has a reset input: RESET. By activating this input the calculated
temperature is reset to its default initial value. This is useful during testing when
secondary injected current has given a calculated "false" temperature level.
ö
- Q
operate
÷
÷
- Q
ø
n
ö
Q - Q
final lockout release _
÷
÷
Q - Q
ø
final n
1MRK 506 382-UEN A
(Equation 33)
(Equation 34)
Line distance protection REL650 2.2 IEC
Technical manual