the temperature of the object is above the set lockout release temperature setting
ResLo
.
The time to lockout release is calculated, That is, a calculation of the cooling time to
a set value.
_
_
ln
final
lockout release
lockout release
final
n
t
t
æ
ö
Q
- Q
= - × ç
÷
ç
÷
Q
- Q
è
ø
EQUATION1177 V1 EN
(Equation 55)
In the above equation, the final temperature is calculated according to equation
.
Since the transformer normally is disconnected, the current I is zero and thereby the
Θ
final
is also zero. 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 start signal START, the estimated time
to trip is continuously calculated and given as analogue output TTRIP. If this
calculated time get less than the setting time Warning, set in minutes, the output
WARNING is activated.
1MRK 504 135-UEN A
Section 8
Current protection
177
Technical manual
Summary of Contents for ret650
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