Insulation Resistance Measurement And Monitoring System - Omron K7GE-MG User Manual

1-4 Insulation Resistance Measurement
and Monitoring System
K7GE-MG is automated according to the procedure of manual measurement and monitoring by
Megohmmeter.
The flowchart of measurement and monitoring of K7GE-MG is shown below together with manual
measurement by Megohmmeter.
Megohmmeter
Step Manual measurement by the Megohmmeter
0 Load operation in progress
Turn OFF the contactor and disconnect the loads from
1
the power line
2 Wait for the loads to stop completely (visual)
Wait for the discharge of electric charge accumulated
in the wiring
3
(Decide the time through experience or residual
voltage measurement)
4 Place the probe on the load and apply Megger voltage
Wait for the measurement value to stabilize (charging
5
time to the wiring capacity)
6 Read the insulation resistance value
7 Remove the probe from the load
Determine if the measurement value is normal or an
8
error
9 If there is more than one load, measure the next load
Record the measurement value and end the series of
10
operations
Insulation Resistance Monitoring Device User's Manual (N224)
MC-a
MC
Auxiliary
MC-a
contact
MC
OFF
Note The above diagram shows only the parts of the internal
circuit of the K7GE-MG that are necessary for explanation.
Step Automatic measurement by the K7GE-MG
Waits until the auxiliary contact turns OFF (trigger
0
signal ON)
Trigger signal ON with the contactor OFF
1 → Measurement operation starts when the trigger
signal is ON
Waits for the loads to stop completely
2 (automatic standby based on setting parameters,
default value: 10 s)
Performs forced discharge of electric charge by the
built-in resistor of the K7GE-MG
3
(Waits for 20 s while limiting the peak value of the
discharge current to 1 mA max.)
Internal contact of the Probe Unit turns ON, and
4
application of the Megger voltage starts
Applies Megger voltage until the measurement value
stabilizes
5 (Continues the measurement for the time set in the
Time to Wait to Stabilize setting parameter, default
value: 60 s)
6 Measures the insulation resistance value
The contact of the Probe Unit turns OFF, and
7
application of the Megger voltage stops
Compares the set alarm value and measurement
8
value, and performs alarm output
9 If there is more than one load, measures the next load
Check the measurement value from the display on the
10
front part, or read and record it remotely
1 Overview
K7GE-MG
Start measurement
L3
Discharge
of electric
charge
Apply
Megger
voltage
PE
1 - 7
1