Zero-Sequence Voltage Unit - ABB REJ 527 Technical Reference Manual

REJ 527
4.1.4.3.
18
Directional or Non-Directional Earth-Fault Relay
Technical Reference Manual
When the earth-fault current exceeds the set start value of high-set stage I
earth-fault unit will start to deliver a start signal after a ~ 60 ms' start time. When
the set operate time elapses, the earth-fault unit will deliver a trip signal.
It is possible to block the start and the tripping of an earth-fault stage by applying an
external binary input signal to the relay.
The inverse-time function of stage I
starts with a switch of switchgroup SGF2. In this case the operate time will be
determined by stage I >>.
0
The high-set stage can be set out of operation. This state will be indicated by dashes
on the LCD and by "999" when the set start value is read via serial communication.
The set start value of stage I
e.g. when the object to be protected is connected to a distribution network. Thus a
set start value below the connection inrush current level can be selected for stage
I >>. A start situation is defined as a situation where the earth-fault current rises
0
from a value below 12% x I
start situation ends when the current falls below 125% x I

Zero-sequence voltage unit

When the zero-sequence voltage exceeds the set start value of low-set stage U
the voltage unit will start to deliver a start signal after a ~ 70 ms' start time. When
the set operate time at definite-time characteristic elapses, the voltage unit will
deliver a trip signal.
The two current stages, I
stages, low-set stage U
0
sequence voltage module. All three voltage stages measure the same voltage but can
have separate settings both regarding sensitivity and operate time. The signalling
and trip relays can also be selected separately for all three stages.
When the zero-sequence voltage exceeds the set start value of low-set stage U
voltage unit will start to deliver a start signal after a ~ 70 ms' start time. When the
set operate time at definite-time characteristic elapses, the voltage unit will deliver
a trip signal.
When the zero-sequence voltage exceeds the set start value of high-set stage U
the voltage unit will start to deliver a start signal after a ~ 60 ms' start time. When
the set operate time elapses, the voltage unit will deliver a trip signal.
It is possible to block the start and the tripping of a voltage stage by applying an
external binary input signal to the relay.
High-set stage U >> can be set out of operation. This state will be indicated by
0
dashes on the LCD and by "999" when the set start value is read via serial
communication.
> can be set to be inhibited when stage I
0
>> can be automatically doubled in a start situation,
0
> to a value above 150% x I
0
> and I >>, can be replaced by two additional voltage
0 0
> and high-set stage U >>, to create a three-stage zero-
0
1MRS 750616-MUM
>>, the
0
>>
0
> in less than 60 ms. The
0
>.
0
>,
0b
>, the
0
>>,
0