Internal Block Diagram - Omron K7GE-MG User Manual

1 Overview
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Internal Block Diagram

This is an internal block diagram of the state when the Main Unit and the Probe Units are connected.
The following describes the main configuration elements.
Main Unit
RS-485
ALM 1 and ALM 2
outputs
Self-diagnosis
error output
Status output during
measurement
 Trigger Input
Connect an external contact, and then starts the measurement operation by a signal from this
contact.
When the auxiliary contact of a contactor is connected to a trigger input terminal as an external
contact, the measurement operation can be started at the time the contactor is turned OFF, that is,
when the load is turned OFF from the power line.
 Voltage Monitoring
The voltage in the load lines is monitored to determine whether the load is turned ON or turned OFF.
This monitoring is performed at all times, and even when the measurement start signal is input, the
measurement operation does not start if the load is turned ON. Also, even if measurement is
progressing normally, it immediately stops if the load is turned ON during the measurement.
 Discharge of Electric Charge
A parasitic capacitance component due to the wiring is present between the charged sections of the
load and the PE. Therefore, even if the contactor is turned OFF, the electric charge accumulated in
the parasitic capacitance component is not discharged immediately. It would take several minutes
for the electric charge to be discharged naturally, so this circuit forcibly discharges the charge. In the
case of a simple short circuit, excessive short-circuit current flows instantaneously, and therefore, by
having a resistance component, the current can be limited to a level where it does not cause any
problem. This processing for the discharge of electric charge is performed before the application of
a Megger voltage.
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Trigger
input
Display
switch
Measurement
RS-485
driver
Microcomputer
Megger
voltage
Power supply
MC-a
MC
M
Probe Unit 1
PE
Discharge Apply
of electric Megger
charge voltage
Current
PE
limiter
MGR
I/O Bus
Insulation Resistance Monitoring Device User's Manual (N224)
MC
M
L3 L2
Voltage
monitoring
Probe Unit 2
Probe
Display
Unit
switch
control
...