Megger SCITS100 Mode D'emploi page 2

General Description
The SCITS100 Secondary Current Injection Test Set has been designed to provide the facilities for testing mains
power supply protective devices, such as relays, overload coils, and circuit breakers. It is built into a strong
transportable metal case and has a splashproof control panel fitted into the top. This control panel contains all the
switches, meters, terminals etc. which are protected by a robust plastic cover when not in use. The connecting leads
for the Test Set are contained in a canvas case stored beneath the cover.
The model can be used with two supply voltage ratings, 240 V 50 Hz/60Hz and 220 V 50 Hz/60 Hz. Five fully variable
output modes are available with fuse, thermal and overload protection and the Test Set has a built-in counter unit.
The output modes are:–
It is important to note that at the high current level on the three main outputs (a), (b) and (c) a duty cycle applies, also
that the d.c. voltage (d) is not a floating output but is obtained by rectification of the 0 — 240 V a.c. output (c). Full
details of the performance of the Test Set are given in the specification.
An optional SF30 Filter Unit is available for testing saturating core type relays to ensure that the test current has a
substantially sinusoidal waveform.
The illustration on page 5 shows the components on the control panel and their function is briefly described below:–
Power Input
The main supply lead is permanently connected through a strain relieving gland. The input power ON/OFF switch is
connected in circuit before the main input fuses for safety. The 1A (T) fuse protects the electronic and measuring
circuits while the 10 A fuse gives protection to the complete instrument and its high current circuits.
Main Output Terminals
The three main output modes each have a separate terminal which is referred to a 'floating' common terminal.
The Test Set is earthed through the mains supply lead, although a separate earth terminal is provided for connection
to a known earth point. In this way, the operator does not rely solely on the earthing of the supply.
Set/Test Switch
With the switch in the '0' position the main output terminals are de-energized.
With the switch in the 'Set' position the injected current or applied voltage available at the main output terminals may
be set using the main output control. This may be done without interruption by the tripping contact on the relay under
test. The Test Set's counter is disabled in this position.
With the switch set to the 'Test' position, the current/voltage previously set-up is now applied in a complete test in
which the relay operates normally and the output from the Test Set is tripped off at the appropriate time. The Test
Set's counter is in operation in this position.
Main Output Control
This controls the output available from all the terminals, except the 0 — 120 V a.c. terminals. It is used in conjunction
with the 'Set/Test' switch to set the output level required. The indicating light adjacent to it illuminates when the
'Set/Test' switch is in the 'Set' or 'Test' positions, indicating an output is present at the terminals.
As a safety feature, the control is fitted with a zero start interlock such that if a power failure occurs during a test the
output is not re-established until the test conditions have been reset.
Ammeter/Voltmeter and Range Switch
The current to be injected or the voltage to be applied during a test is shown on a 3
below this display sets the range for the metering only; it does not affect the output level.
240 V d.c. Output Terminals
These are low current (0 — 1 A) output terminals. Output is derived from unsmoothed full wave rectification of the
0 — 240 V a.c. and is protected by a 1 A HBC fuse.
120 V a.c. Output
Output from the 0 — 120 V a.c., 0,5 A terminals is derived from a separate auxiliary output control mounted at the
top right of the panel. This output is fully floating and is protected by a 0,5 A fuse. Control is only by means of the
auxiliary output and is completely independent of the main output control. As a safety feature, the control is fitted with
a zero start interlock.
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(a) 0 — 100 A 0 — 24 V a.c.
(b) 0 — 30 A 0 — 80 V a.c.
(c) 0 — 10 A 0 — 240 V a.c.
(d) 0 — 240 V 0 — 1 A d.c.
(e) 0 — 120 V 0 — 0,5 A a.c.
⁄ digit l.e.d. display. The switch
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