4 2
S V E R K E R 7 5 0 / 7 6 0
P r o g r a m m a E l e c t r i c A B
Z P - C D 0 1 E R 0 5 A
6.6 Finding pick-up
and drop-out limits for
over (current/
voltage/other entity)
relays
Method 1a: Normal injection,
gradual increase in current.
Current is generated continuously. This procedure is
suitable in situations where there is little risk of
overheating the protective relay equipment and you
wish to measure the drop-out function without using
a second test procedure.
1.
Initial settings: OFF. Main knob at 0.
2.
Connect the relay’s current input and
tripping output to Sverker.
3.
Use the button marked A to transfer the
ammeter test point to the selected output.
4.
Set the timer stop condition (to CLOSURE
+ OPENING, CONTACT for example).
5.
Activate ON using the start switch.
6.
Turn up the current until the relay operates
(pick-up).
7.
Read the current.
8.
Turn down the current. Read the current
that flows when drop-out takes place.
9.
Interrupt output by setting the start switch
to OFF.
Method 1b: Normal injection, pick-
up and drop-out values obtained
using the HOLD (freeze) function
Increase the current gradually until the relay oper-
ates, whereupon the current reading is frozen. You
can then start reducing the current immediately, and
the current reading will be frozen when drop-out
occurs.
1.
Initial settings: OFF. HOLD. Main knob at 0.
2.
Connect the relay’s current input and
tripping output to Sverker.
3.
Use the button marked A to transfer the
ammeter test point to the current output
that is being used.
4.
Set the timer stop condition (to CLOSURE
+ OPENING, CONTACT for example).
5.
Activate ON using the start switch.
6.
Turn up the current until pick-up.
7.
The tripping limit will be frozen and held on
the display.
8.
Press the HOLD button twice in order to
reset the HOLD function.
9.
Turn down the current until the relay drops
out. You can now read the frozen drop-out
value from the display window.
10. Interrupt output by setting the start switch
to OFF.
Method 2: Manually-controlled
(momentary) injection
Here, the current is interrupted when you release the
start switch (from the ON or ON+TIME position).
This procedure enables you to prevent overheating
of the protective relay equipment when, for exam-
ple, you are trying to find the pick-up value for an
instantenous unit.
1.
Initial settings: OFF. MOMENTARY (see
explanation of settings in Chapter 5).
HOLD. Main knob at 0.
2.
Connect the relay current input and tripping
output to Sverker.
3.
Use the button marked A to transfer the
ammeter test point to the current output
that is being used.
4.
Set the timer start condition to INT.
5.
Set the timer stop condition (to CLOSURE
+ OPENING, CONTACT for example).
6.
Change the main knob setting.
7.
Activate ON briefly. The duration of the
output must be longer than the operating
time of the instantaneous unit. If you want
to check the time, you can activate
ON+TIME instead of ON.
8.
Check to see that the instantaneous unit
has tripped. This can be done by a) check-
ing the indicator lamp on the relay or b)
checking to see that the TRIP indicator
lamp in Sverker is on and that the meas-
ured operating time matches the operating
time of the protective relay equipment.
Repeat, starting with step 6, until you find
the lowest current that provides operation.
9.
Read the current.
10. To measure the drop-out value, activate ON
again using the start switch until tripping
occurs. Then, while keeping ON active,
Summary of Contents for Programma Sverker 750
Page 1: ...SVERKER 750 760 User s manual Relay Test Unit ...
Page 28: ...2 9 S V E R K E R 7 5 0 7 6 0 P r o g r a m m a E l e c t r i c A B Z P C D 0 1 E R 0 5 A ...
Page 75: ...7 6 S V E R K E R 7 5 0 7 6 0 P r o g r a m m a E l e c t r i c A B Z P C D 0 1 E R 0 5 A ...
Page 76: ...Subject to change without notice Printed matter ZP CD01E R05B 2007 ...
