ABB RET650 Technical Manual page 183

1MRK 504 135-UEN A
Technical manual
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.
æ
t
= - × ç
t ln
ç
lockout release _
è
EQUATION1177 V1 EN
In the above equation, the final temperature is calculated according to equation 49.
Since the transformer normally is disconnected, the current I is zero and thereby the
Θ is also zero. The calculated component temperature can be monitored as it is
final
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.
ö
Q - Q
final lockout release _
÷
÷
Q - Q
ø
final n
Section 8
Current protection
(Equation 55)
177