Testing The High-Set Overcurrent Stage; Testing The Definite Time Overcurrent Stage; Testing The Inverse Time Overcurrent Stage - Siemens 7UT51 Instruction Manual

16
Bench Testing
16.6.1 Testing the High
Overcurrent Stage
Testing can be performed with single-phase,
two-phase or three-phase test current. When
assessing the currents, it must be considered that the
current that is evaluated by the relay is referred to the
rated current of the protected object or transformer
winding.
Test currents larger than four (4) times In
or 15A (Sensitive input) may overload
and damage the relay if applied
continuously.
Observe a cooling down period!
For testing the 50HS stages, therefore, measurement
shall be performed dynamically. It should be noted that
the relay picks up at 1.1 times the setting value and
does not at 0.9 times setting value.
When the test current is injected, the pickup indication
of the 50HS stage, annunciation "Backup 50HS",
appears. After expiration of the time delay, trip signal
is given (LED 4 at deliver and annunciation "Back
Gen. Trip"). If the protection is switched On, the
assigned trip contacts close.
It must be noted that the set times are pure delay
times, operating times of the measurement functions
are not included.
16.6.2 Testing the Definite Time
Overcurrent Stage
For the test, the Definite Time mode must be selected
in Address 2111.
The rated object current is to be considered.
When the set value for 50T (Address 2112) is
exceeded, the pickup indication "Backup I>/Ip"
appears.
After the expiration of the time delay in Address 2113,
trip signal is given (LED 4 and annunciation "Back
Gen. Trip"). If the protection is switched On, then the
assigned trip contacts close.
172
Set
It must be noted that the set times are pure delay
-
times, operating times of the measurement functions
are not included.
16.6.3
For these tests, one of the Inverse Time modes must
be selected in Address 2111.
The rated object current is to be considered.
When the test current is increased above 1.1 times the
set value 51PU (Address 2114), pickup indication
appears ("Backup I>/Ip").
The time delay depends on which characteristic has
been selected in Address 2111 and the set time
multiplier in Address 2115. The expected time delays
can be calculated or read from the characteristic
curves. Be certain to consider current matching
factors.
Testing the Inverse Time
Overcurrent Stage
Test currents larger than four (4) time In
or 15A (Sensitive input) may overload
and damage the relay if applied
continuously.
Observe a cooling down period!
7UT51 v3
PRIM-2330C