Inverse-Timer Freezing - ABB 615 series Technical Manual

Section 11
General function block features
11.2.3
1110
The delayed inverse-time reset is not available for IEC-type inverse time
curves.
User-programmable delayed inverse reset
The user can define the delayed inverse reset time characteristics with the following
formula using the set Curve parameter D.
 
 
D
 
t s [ ] = k
⋅
 2 
I
 
 
1
 −

 
I
>
 
 
A060817 V3 EN
t[s] Reset time (in seconds)
Time multiplier
k set
Curve parameter D
D set
I Measured current
I> set Pickup value

Inverse-timer freezing

When the BLOCK input is active, the internal value of the time counter is frozen at the
value of the moment just before the freezing. Freezing of the counter value is chosen when
the user does not wish the counter value to count upwards or to be reset. This may be the
case, for example, when the inverse-time function of a protection relay needs to be
blocked to enable the definite-time operation of another protection relay for selectivity
reasons, especially if different relaying techniques (old and modern relays) are applied.
The selected blocking mode is "Freeze timer".
The activation of the BLOCK input also lengthens the minimum delay
value of the timer.
1MAC059074-MB A
(Equation 178)
615 series ANSI
Technical Manual