ABB RES670 Technical Manual page 255

1MRK 511 408-UUS A
Phasor measurement unit RES670 2.2 ANSI
Technical manual
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 trip with the present current. This
calculation is only performed if the final temperature is calculated to be above the
operation temperature:


   
final
t ln

trip


final
ANSIEQUATION1169 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
Q
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 MULTPU 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.

 
trip


 

n
ö
- Q
final lockout release _
÷
÷
Q - Q
ø
final n
Section 8
Current protection
(Equation 25)
(Equation 26)
249