ABB RER620, Техническое руководство

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1MAC309294-MB F
Section 10
General function block features
RER620 533
Technical Manual
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 .
(Equation 63)
t[s] Reset time (in seconds)
k set Time multiplier
D set
Curve parameter D
I Measured current
I> set
Pickup value
10.2.3 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 relay needs to be blocked to enable
the definite-time operation of another relay for selectivity reasons, especially if different
relaying techniques (old and modern relays) are applied.
Activating the
BLOCK
input alone does not affect the operation of the
PICKUP
output. It
still becomes active when the current exceeds the set Pickup value , and inactive when the
current falls below the set Pickup value and the set Reset delay time has expired.
The delayed inverse-time reset is not available for IEC-type inverse time
curves.
t s
D
I
I
k [ ] =
>
⎛
⎝⎜ ⎞
⎠⎟
−
⎛
⎝
⎜
⎜
⎜
⎜⎜
⎞
⎠
⎟
⎟
⎟
⎟⎟
⋅
2
1
The selected blocking mode is “Freeze timer”.
The activation of the
BLOCK
input also lengthens the minimum delay value
of the timer.