Voltage Monitoring - Omron K7GE-MG User Manual

4 Functions Related to Measurement
4-4

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 trigger signal is ON or when the K7GE-MG moves
to manual measurement, the measurement operation
is not started 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.
If the load is determined to be turned ON following
trigger signal ON, it results in "measurement failed",
and the alarm output turns ON. Refer to Timing Chart for Measurement Failure on page 4-12 in 4-1-4
Timing Charts on page 4-8 for information on the operation when measurement fails.
Next, the judgment conditions for the voltage monitoring function are described.
The voltage value and voltage waveform differ
depending on the type of load and the drive
method. To detect the waveform, the K7GE-MG
monitors the peak value of the waveform.
The threshold value is set as approx. 20 V, and if
the absolute value of the peak value is larger than
this, it is judged that voltage is present (load
turned ON), and if it is smaller than this, it is
judged that voltage is absent (load turned OFF).
Therefore, this function is also applicable to loads
having a 24 VDC drive.
Moreover, in the case of alternating current waveforms such as sine waves, thyristor control, and
inverter control, a frequency of 20 Hz or more is required. For a frequency lower than 20 Hz, it takes too
much time from the detection of a waveform until the detection of the next waveform, and it may be
judged that voltage is absent (load turned OFF).
The highest voltage that can be monitored is 600 VAC rms (+10%) of sine waves or commercial
frequencies.
4 - 22
MC
Note The above diagram shows only the parts of the
internal circuit of the K7GE-MG that are
necessary for explanation.
Direct current
Sine wave
Thyristor control
Inverter control
Insulation Resistance Monitoring Device User's Manual (N224)
K7GE-MG
L2
Voltage
L3 To the microcomputer
monitoring