Mdu Detailed Specifications; Precautions For Measurement - Mitsubishi Electric MDU-BN Instruction Manual

6. MDU Detailed Specifications

6.1 Precautions for measurement

(1) Electric current measurement accuracy
The MDU electric current measurement accuracy is ± 1.0% of the maximum current setting (measurement rated current) of the circuit breaker.
For example, the permissible difference of NF400-SEW with MDU is 4.0 A (400 A × 1.0%), so the permissible difference from a current of 0 A to
400 A would be ± 4.0 A.
If the measurement value is less than 1.0%, the display value is cut off to 0 A. However, if the current is 0.4% or more of the rated value, the electric power
and electric energy are measured.
(2) Demand value
The demand value is generally the average value over the demand time limit.
The demand time limit (to) is the time until the measurement display value (lo) when a fixed input (I) is continuously powered displays 95% of the input (I).
It will take an amount of time roughly equal to three times the time limit (to) to display 100% of the input (I).
(3) Power factor measurement accuracy
The MDU power factor measurement accuracy is 5% versus the 90 ° electric angle.
This is phase angle 4.5 ° . With regard to power factor this means that a display value up to around 0.3% (LEAD (forward) 99.7 to LAG
(delay) 99.7) at 100% and around 6% (64.9 to 76.0) at 70.7% of LEAD or LAG will be allowed.
Measurement value
4.0 A
4.0 A
4.0 A
0 A
I
0.95 I
Io
Measurement
display value
-99.7%
-70.7%
±
5%
of 90 °
±
4.5 °
Forward (LEAD)
-45 °
Permissible
error range
400 A Input value
to
t (Time)
(time limit)
Power
factor
100%
Permissible error range
+99.7%
Permissible error range
76.0%
70.7%
64.9%
±
4.5 °
Delay (LAG)
0 ° 45 °
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