Function - Bender A-ISOMETER IR1570 Series Operating Manual

Function

2.4 Function
The A-ISOMETER® IR157x is connected between the unearthed system and
the protective conductor (PE).
The response values and other function parameters are set via the function
keys. The parameters are indicated on the LC display and are stored in a nonvolatile
memory (EEPROM) after the setting is completed.
IR1570:
A DC measuring voltage is superimposed on the AC system to be monitored.
IR1575:
A microprocessor-controlled pulsating AC measuring voltage is superimposed
on the AC system to be monitored (AMP measuring principle, "adaptive
measuring pulse", developed by BENDER; European Patent:
EP 0 654 673 B1). The measuring cycle consists of positive and negative pulses
of the same amplitude. The period depends on the respective system leakage
capacitances and the insulation resistances of the system to be
monitored.
An insulation fault between system and earth closes the measuring circuit.
From the measured current value, the microprocessor calculates the insulation
resistance which is indicated on the LC display or the external kÙ measuring
instrument.
The measuring time is determined by the system leakage capacitances, the
insulation resistance, and the system-related interference disturbances. System
leakage capacitances do not influence the measuring accuracy.
If the reading is below the selected response values Alarm 1/Alarm 2, the associa-
ted alarm relays respond and the alarm LEDs "Alarm 1/2" light up and
the measuring value is indicated on the LC display (in the event of DC insulation
faults, the faulty supply line is indicated). If the terminals R1/R2 are
bridged (external RESET button [NC contact] or wire bridge), the fault indication
will be stored. Pressing the RESET button, resets the fault message,
provided that the currently displayed insulation resistance is at least 25%
above the actual response value. The fault memory behaviour can also be setin the
"ISO SETUP" menu, by selecting the sub menu Memory: on/off.
By pressing the TEST button, the function of the A-ISOMETER® IR157x in
can be tested. In this way, all essential measuring functions as well as connections
to the system and to earth are checked. This self-test is automatically
carried out every 24 hours. In addition the self-test is automatically carried
out after the supply voltage has been switched on.
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TGH1370en/12.2019