Mitsubishi Electric MELSEC iQ-R Series User Manual page 141

Section 8 TROUBLESHOOTING
8.3 Q&A
8.3.1 General
To what degree is the module durable against overvoltage and over current? Is external protective circuit
Q
required?
Momentary* : Up to 2 times as high as rated voltage and 20 times as high as rated current.
Continuous : Up to 1.1 times as high as rated voltage and rated current.
A
* Momentary means: Energizing 9 times for 0.5 seconds at 1-minute intervals, and then 1 time for 5 seconds.
External protective circuit is not required.
Q Can the module be used as an electric energy meter?
This module can be used to measure the electric energy and to manage the use of electric energy.
A However, it cannot be used for deal and proof of electric energy measurement stipulated in the measurement
law.
Q Are errors in wiring verifiable easily?
They are verifiable by the illuminating condition of "MEA.", "R," "1," and "3" LEDs on the front of the module.
A
Refer to "8.2.3" for details.
Q Is it OK to open the secondary terminals of the current sensor?
The secondary side of the dedicated current sensor is equipped with the protective circuit against opening of
A
secondary terminals. Opening them during the wiring work causes no problems. However, for safety, please
do not continuously energize the module with the terminals open.
Q Is measurement of inverter circuit possible?
Measuring the secondary side of the inverter is impossible due to the large fluctuation of frequency.
Make measurement on the primary side of the inverter. However, since a current waveform on the primary
A
side of the inverter has a distortion containing the harmonic components, a slight difference may occur.
Q Obtained values may be different from other measuring instruments. Why is it so?
There are various possible causes. Check the following first, please:
[1] Check for wiring errors (polarity of current sensors, connections of current circuits, and connections of
voltage circuits, in particular).
[2] On the split-type current sensor, check for the poor engagement or separation of fitting surfaces.
[3] On the split-type current sensor, check for pinching of foreign object between fitting surfaces.
[4] Check that the measuring instrument used for comparison indicates a correct RMS value.
A
[5] If the measuring instrument used for comparison measures an average value instead of RMS value,
distortion in the current of the circuit to be measured causes a significant difference of values. This
module measures an RMS value.
[6] Check for the short-circuit on the secondary side of the current transformer (CT).
[7] Only a dedicated current sensor is connectable to module. Check that the proper current sensor is
connected or not.
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