|
The SCITS100
Secondary Current Injection Test Set has a maximum rating of
100 A/1,8 kVA and a built-in timer unit. The test set is
constructed in a rugged metal case with large carrying
handles for practical field operations. The SCITS100 will
test instantaneous relays, IDMT relays, directional relays,
molded circuit breakers and metering.
Current or voltage
at each of the three main sets of a.c. terminals is
completely variable by use of the main output control. The
outputs from these terminals are:
-
0 to 100 A
ac or 0 to
24 V ac
-
0 to 30 A
ac or 0 to
80 V ac
-
0 to 10 A
ac or 0 to
240 V ac
The rms current
output, flowing via the common terminal, is measured to a
resolution of 10 mA. Also incorporated are a variable 0 to
240 V d.c. output and an independently controlled 0 to 120 V
a.c. output to allow directional relays to be tested.
Two digital LED
displays are used, one to show the level of the output
voltage or current (in conjunction with a
meter range switch) and the other to record the readings
from the built-in timer. A SET/TEST switch is provided so
that the appropriate test current can be set up before the
test is actually carried out, and to avoid damage to relay
coils by disconnecting the test current after the relay has
operated.
The timer facility
has three custom operating modes: NORMAL, RUNBACK and
MANUAL. These enable the function of a protective
relay to be fully tested. Separate terminals are
provided for connecting to the tripping
contacts of the relay. The counter has a RESET pushbutton
and two manual tripping pushbuttons, one of which is a
remote hand-held control for use when testing relays
situated high up on switchgear.
A bimetallic sensor
on the main output transformer prevents overheating and a
thermo-magnetic resettable cutout gives instrument
protection in the event of an overload.
An SF30 Filter Unit
is available for use when testing saturating core-type
relays to ensure that the test current
has a substantially sinusoidal waveform. It is connected in
series with the output of SCITS100 and corrects the
waveform distorted by saturated cores in the device under
test. (See the waveform diagram).
Applications
Protective devices such as
relays, overload coils and circuit breakers must be checked
on installation and at regular intervals while in service to
ensure that they are always ready to operate correctly if a
fault should occur in the equipment that they are
protecting. Routine current injection testing will quickly
detect faulty or incorrectly adjusted protection devices.
Also, it will possibly prevent serious damage to plant
equipment and maybe injury to personnel.
The SCITS100 is
suitable for all these applications and particularly for
testing protective relays, including IDMT
relays.
As well as checking
that a protective device functions correctly, it is usually
necessary to measure its operating
time. The SCITS100 has its own built-in timer unit with the
option of control by a remote pushbutton.
Current injection
test sets are ideal for any application in which it is
necessary to supply a low-impedance load with a controlled
and measured heavy current.
|
