20
measurements can be made at the rated current
of the relay. It should be noticed that the relay
shows the measured current as a multiple of the
rated current I
n
of the energizing input occu-
pied.
Checking of
matching
transformers
The matching transformers of the protection
relay are tested separately for each phase. A pure
sinusoidal current is fed to the relay. The current
value indicated in the display of the relay should
be equal to that indicated by the ammeter. The
The switches of switchgroup SGR should be set
as follows:
Switch
Position
1
1
2
0
3
1
4
0
5
0
6
0
7
1
8
0
Then the following signals are linked to the
output relays:
Output
Function
(terminals)
A (65-66)
Tripping of stage I>
B (68-69)
(Tripping of stage I>>)
C (80-81)
Signal on tripping of stage I>
(LED L3)
D (77-78)
Start of stage I> (LED L2)
E (71-72)
Signal on internal relay fault
(LED L1)
Starting
The start function for one phase is tested in
accordance with Fig. 8. When required, the test
can be repeated separately for each phase. The
test current is slowly increased until the relay
starts (LED L2 is lit) and the value of the current
at starting is read on the ammeter.
Operate time
Definite time characteristic
The operate time of the overcurrent relay is
measured at a test current equal to 2 x the setting
value of stage I>. The timer is started by closing
switch S1 and stopped by contact 65-66 on
operation of output relay A.
The operation of output relay C is indicated by
lighting of LED L3.
When the relay starts, the yellow indicator I> in
the right bottom corner of the front panel of the
relay module is lit, and when the relay trips it
turns red.
Inverse time characteristic
At inverse time characteristic the operate time of
the relay is measured at two current values (2 x
I> and 10 x I>). The operate times thus received
are compared with the operate times shown in
the current/time curves for the corresponding
inverse time characteristic.
Blocking
Switches 4 and 5 of switchgroup SGB on the PC
board of the relay module are to be set in
position 1 (ON). Switch SGR/1 on the system
panel, too, has to be in position 1.
The blocking function is tested by applying a
control voltage of the auxiliary voltage level to
input 10-11 via switch S2. At first switch S2 is
closed and then the test current is encreased well
above the set start current level.The relay will
start, i.e. L2 is lit, but it must not operate, i.e. L3
remains dark.
Testing of low-set
current stage I>
