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Siemens AG 6SE8004-0BH76
SIMOVERT MV Commissioning Instructions
29
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The connections to the line supply and ground (PE) are permanently monitored. If
the cables/conductors are interrupted, are not connected or there is a very high-
ohmic connection, "ALARM E-KE" or "ALARM L1-L3" signals are displayed on the
LCD.
In this case, immediately check all of the connecting cables, as the insulation
resistance cannot be correctly measured.
In new or small IT supply networks, the insulation resistance can lie in the range
> 20 M
Ω
. In this case, the message is also output. In this case, the connection
monitoring must be disabled in Setup2.
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The system comprises the coupling device AGH5205 with series resistor and the
evaluation unit A-ISOMETER IRDH265-.. (refer to connection circuit-diagram).
The unit is mounted in a plastic housing and can be snapped-onto a mounting rail,
in accordance with DIN EN 50022; it can also be screwed to a panel.
The AGH520S coupling device is connected upstream of the A-ISOMETER
through series resistors to couple to the voltage to be monitored and to limit the
measuring current under fault conditions.
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The A-ISOMETER type IRDH265 is connected between the ungrounded line
supply and the potential bonding conductor (PE).
Operator keys <4, 5, 6> are used to set the response values and other function
parameters. The parameters are shown on the LCD display and are saved in a
non-volatile memory (EEPROM) after the setting has been completed.
A microcontroller-based pulse-shaped alternating measuring voltage is
superimposed on the line supply. The measuring pulse comprises positive and
negative pulses of the same amplitude. The period depends on the particular
discharge capacitances and the insulation resistances of the line supply to be
monitored. The measuring circuit is closed if an insulation fault occurs between the
line supply and ground. The evaluation circuit determines the insulation resistance,
which is indicated on the LCD display after the measured value sensing time.
The measured value sensing time is a function of the line discharge capacitance,
the insulation resistance as well as possible line-relevant faults. Line discharge
capacitances do not influence the measuring accuracy.
When the selected response values ALARM1 / ALARM2 are fallen below, the
associated output relays <11, 12> respond, the signaling LED "ALARM1/2" <1, 2>
is lit (goes bright) and the LCD display <7> indicates the measured value. If the LT
terminals are jumpered (external RESET button <9> [NC contact] or wire jumper),
the fault signal is saved.
The function of the A-ISOMETER IRDH265 can be tested using test button <3>.
"TEST" is displayed after the test button is pressed (> 2 s). If a fault is not
identified, "TEST OK R < 1 kOhm" is displayed after the response time has
expired, the output relays switch, and both signaling LEDs light-up (go bright). If a
system fault is identified during the test, "TEST ALARM" is displayed on the LCD.
The faults are acknowledged by pressing the "TEST/RESET" button <3> (< 1 s).
