Mitsubishi EMU4-BM1-MB User Manual page 38

■Q&A about specifications
Q
What does "Allowable tolerance" mean?
In terms of the amount of electricity, it means a range of tolerances in reading values. For example, when the reading value is "10 kWh,"
A
a tolerance is ±0.2 kWh. In terms of measured elements other than the amount of electricity, it means tolerance for the rated input. For a
current, when a rated current is set to 250 A, 2.5A(±1%) is a tolerance.
Q
Is accuracy of a current sensor included?
Accuracy of a current sensor is not included in accuracy of the unit.
A
A maximum value of tolerance is obtained by summing tolerance of the unit and that of a current sensor.
Q
To what degree an area of micro current is measured?
A current value is measured from the area exceeding 0.4% of the rated current. In an area below 0.4%, measurement result is indicated
as "0" (zero). However, in that case, still, the amount of electricity is being measured. Even if the indicated value is "0," measurement
value will increase in continuing measurement for a long time.
The amount of electricity is measured with a load that is about 0.4% or more of all load power.
A
Current value is measured when it is more than setup value of cut-off. Measured value is 0 when it is less than setup value of cut-off.
Measured value of electric energy value is increased even thought displayed current is 0, because electric energy measuring is
conducted.
Electric energy is measured when the load is more than about 0.4% of full load.
Q
Is measurement of inverter circuit possible?
Measuring the secondary side of the inverter is impossible due to the large fluctuation of frequency.
A
Make measurement on the primary side of the inverter. However, since a current waveform on the primary side of the inverter has a
distortion containing the harmonic components, a slight error occurs.
■Q&A about installation
Q
What is wire diameter that allows installing a current sensor?
The following lists the nominal cross-sectional areas of the conductor of 600-V vinyl coated wires that can penetrate. (values for
reference)
･ IV wire (600-V vinyl insulated wire)
38mm 2
（EMU-CT50-A） 、60mm
200mm 2
（EMU-CT250-A） 、500mm
A
･ CV wire (600-V vinyl insulated wire)
22mm 2 （EMU-CT50-A）, 38mm
150mm 2 (EMU-CT250 (100mm
400mm 2 （EMU-CT400-A、EMU-CT600-A）, 500 mm
The above shows the standard nominal cross-sectional areas. Due to the outer difference of finished vinyl insulation and deformation
(bending) depending on manufacturers, a wire may not penetrate. Make verification on site.
Q
What are the points when installing a current sensor?
Models EMU2-CT5, EMU2-CT5-4W, EMU-CT***, EMU-CT***-A and EMU-CT5-A are split-type. If split surfaces are not engaged
A
sufficiently or a foreign object exists between the split surfaces, adequate performances are not obtained. Pay attention in installation.
2 （EMU-CT50/CT100, EMU-CT100-A） 、150mm
2 （EMU-CT400-A、EMU-CT600-A） 、500 mm
2 (EMU-CT50/CT100), 60mm
2 is recommended), EMU-CT250A)
2 x 1 wire, 325 mm
37
2
（EMU-CT250）
2 ×1wire、325 mm2×2wire（EMU-CT400/CT600）
2
（EMU-CT100-A）,
2 x 2 wires (EMU-CT400/CT600)