ABB RER620, Technical Manual

Page: 198 / 584

Section 4
1MAC309294-MB F
Protection functions
192 RER620
Technical Manual
Timer
Once activated, the timer activates the respective phase
PICKUP(ST_A_AB)
as shown
typically above for respective phase output as well as the common
PICKUP (START)
output . Depending on the value of the set Operating curve type , the time characteristics
are selected according to DT or IDMT.
When the operation timer has reached the value set by Trip delay time in the DT mode or
the maximum value defined by the IDMT, the
TRIP
(
OPR_A_AB
) for respective phase as
well as the common the
OPERATE
output are activated.
When the user-programmable IDMT curve is selected, the trip time characteristics are
defined by the parameters
Curve parameter A , Curve parameter B , Curve parameter C ,
Curve parameter D and Curve parameter E .
If a drop-off situation occurs, that is, a fault suddenly disappears before the trip delay is
exceeded, the reset state is activated. The behavior in the drop-off situation depends on the
selected trip time characteristics. If the DT characteristics are selected, the reset timer runs
until the set
Reset delay time value is exceeded. If the drop-off situation exceeds the set
Reset delay time , the timer is reset and the
PICKUP
output is deactivated.
When the IDMT trip time curve is selected, the functionality of the timer in the drop-off
state depends on the combination of the
Type of reset curve and Reset delay time settings.
Table 201: The reset time functionality when the IDMT trip time curve is selected
For a detailed description of the voltage IDMT curves, see the General
function block features section in this manual.
Type of reset curve Description of operation
“Immediate” The trip timer is reset instantaneously when drop-off
occurs
“Def time reset” The trip timer is frozen during drop-off. The trip timer
is reset after the set Reset delay time is exceeded
“DT Lin decr rst” The trip timer value linearly decreases during the
drop-off situation. The trip timer is reset after the set
Reset delay time
is exceeded