Megger LCB2000/2 Bedienungsanleitung Seite 22

3. Press the UP and DOWN keys until the required test
current is displayed. Hold a key down to auto-
repeat.
4. Press the ENTER key. The Supply Voltage, Test
Type and RCD Type are shown. These may be set
up as given in the following sections.
Setting precision:
10-50mA
50-500mA
500mA-1000mA
RCD Type
Pressing the key displays the RCD type symbols.
From information given on the RCD to be tested, select
and set the type of RCD, as shown in the table.
1mA steps
5mA steps
10mA steps
Symbol
General
Selective (delayed)
D.C. sensitive
D.C. Sensitive RCDs
Some RCDs are electromechanical devices which can
be saturated by the presence of d.c. Therefore if a d.c.
fault occurs, or an a.c. fault occurs in the presence of
quite a small direct current, the RCD may not trip. In
this way the RCD is disabled and this becomes a
potential hazard. Because of this, 'd.c. sensitive' RCDs
are available.
Selective or Time delayed RCDs
In some cases it may be necessary to have an RCD
protecting an individual circuit or group of circuits. If a
fault occurs, the RCD nearest to the fault should trip to
clear it, maintaining supplies to the other circuits.
Selective RCDs (normal symbol)
discriminate faults occurring on circuits, and these have
a minimum as well as a maximum trip time.
Test
are used to
21