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5 - 6
Siemens AG ⋅ January 1999
Some of the following check steps inĆ
volve exposure to dangerous voltages.
All checks must therefore be carried out
by competent persons in accordance
with the relevant safety requirements
and precautions.
Before connecting the device to the power supply for
the first time, it should be left to stand in the operaĆ
ting area for at least two hours in order to allow the
temperature to adjust and to prevent humidity and
moisture condensation.
D The circuit-breaker of the DC-voltage supply must
be switched off.
D The CT-connection must be checked in accorĆ
dance with the plant and connection diagram:
- Is the current transformer correctly earthed?
- Correct phase allocation of the current transforĆ
mer?
- Uniform polarity of the current transformer terĆ
minations?
D Loop the DC-amp-meter into the auxiliary supply
voltage supply line; range approx. 1.5 to 3 A.
D Switch on mcb for battery voltage (supply protecĆ
tion). The power consumption must correspond
(after a short pointer swing due to the charging
current rush of the storage capacitors) to the noĆ
minal no-load power consumption (approx. 2 W).
D Switch off mcb for direct supply voltage.
D Remove DC-amp-meter; re-establish normal auxiĆ
liary supply voltage connection.
D Switch on circuit-breaker of the DC-voltage supĆ
ply. After maximum 0.5 seconds, the green LED in
the front panel must light up and the red "fault"
indication must extinguish after max. 7 seconds.
D Switch off mcb for direct supply voltage.
D Check trip wires to the circuit-breaker.
D Check control wires to and from other devices.
D Check signaling wires.
D Switch mcb back on
The connection circuit (standard connection) is repreĆ
sented in the appendix A.1 . The three input windings
of the summation transformer permit connection to
the current transformer in a number of different
ways; The most common types of connection are
described below. It is imperative, however, that the
connection type is the same at both line ends. The
marshalling options for the binary inputs and outputs
are described in section 5.5.
The standard connection is suitable for all systems,
irrespective of the earthing of the system's neutral
point. Figure 5.3 shows the current transformer conĆ
nections. In comparison to the symmetrical three-
phase current, the sensitivity for Ph-Ph short-circuits
varies with a factor between 0.58 and 1.15, and those
for earth faults or double earth faults are more sensiĆ
tive with a factor of 1.73 to 2.89. In isolated-neutral
or resonant-earthed systems, the phases can also be
changed cyclically or acyclically in order to adjust the
device to the double earth fault preference which preĆ
vails in the system. To this end, the preferred phase
is connected to the first winding with the factor 2
while the non-preferred phase is not directly connecĆ
ted to the device.
The connection circuit shown in Figure 5.3 therefore
corresponds to the double earth fault preference L1
before L3 before L2. In an electrically connected syĆ
stem, the connection type must be the same at both
ends of the line.
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