ln
final operate
operate
final n
t
t
æ ö
Q - Q
= - ×
ç ÷
ç ÷
Q - Q
è ø
EQUATION1169 V1 EN-US (Equation 32)
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.
_
_
ln
final lockout release
lockout release
final n
t
t
æ ö
Q - Q
= - ×
ç ÷
ç ÷
Q - Q
è ø
EQUATION1170 V1 EN-US (Equation 33)
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.
Section 8 1MRK 505 394-UEN A
Current protection
210 Line differential protection RED650 2.2 IEC
Technical manual
To Next Page
Loading...
