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Chapter 1. Description
1-3
M7IRDA2003I
7IRD-A/J/M: Distribution Protection & Control Terminal
© ZIV APLICACIONES Y TECNOLOGÍA, S.L.U. 2020
1.2
Protection Subsystem Functions
1.2.1
Non-Directional Overcurrent Protection 3-Phase and Ground
Includes four non-directional overcurrent measuring units (three for Phase Overcurrent
protection and one for Ground). On
7IRD-A
and
7IRD-M
models each unit is comprised of a
time element and an instantaneous element, with additional temporization adjustable. On
7IRD-
J
model each unit is comprised of a time element and two instantaneous elements, with
additional temporization adjustable.
Time elements can be selected with the following types of characteristics:
Definite Time
,
Inverse
,
Very
Inverse
,
Extremely
Inverse
and
User Programmable
.
Time and instantaneous overcurrent elements for phase and ground can be enabled or disabled
using settings. Three setting groups are provided for selecting alternative pre-established time
and instantaneous overcurrent pickup values and time characteristics (one is active and two are
in reserve).
Phase and ground, timed and instantaneous overcurrent pickup and tripping functions can all be
individually targeted.
1.2.2
Recloser (7IRD-A/J Models)
Reclosing can be separately coordinated with external protection as well as with the protection
contained in the terminal unit. Reclosing sequences for phase faults and ground faults can be
set independently.
Reclosing is selectable up to a maximum of four attempts with independent settings for
Recloser timers (dead or open breaker wait times) and reset times. The reclosing sequence is
controlled by the breaker position and by the reclose initiate signal, which permits reclosing
based on the protective elements which operated to trip the breaker.
The trip elements and reclose attempts enabled during a fault clearing and reclosing sequence
are selectable.
Manual closing can be initiated from the terminal unit using its reclosing output contacts. The
close command in this instance is supervised and controlled in the same way as any
permissible automatic reclosing command following a trip from the protection elements.
1.2.3
Breaker Failure Protection
The terminal unit incorporates breaker failure protection elements which detect the continuation
of phase or ground overcurrent and send trip commands to initiate backup tripping of other
breakers.
1.2.4
Open Phase Protection
This element detects open phase conditions by measuring the negative-sequence to positive-
sequence current ratio. Detection of the open phase enables tripping should the setting
threshold be exceeded.
1.2.5
Residual Current Detection (Neutral Unbalance Unit)
Three-phase systems where loads are not connected phase-to-ground can benefit from this
function. A trip is permitted if zero sequence current, which does not reach minimum phase-to-
ground-fault levels, is detected for a preset period of time. The presence of the aforementioned
current would indicate the existence of an unacceptable current unbalance.
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Страница 175: ...D List of Illustrations and Tables...