Specifications

9
Selection Precautions
Indicator Line-up,
Precautions & Specifications
Selection of indicator ratings
Application of an input exceeding a rating may cause failure or reduced service life.
In cases where a rating value may be exceeded temporarily due to a starting current of a motor or other reason,
select an expanded scale indicator.
Meter relays respond instantaneously and thus output a signal immediately when the starting current or other
current exceeds a set value.
When it is necessary to temporarily prevent detection, add an external circuit.
Distortion of input waveform
Error occurs readily when the input waveform is distorted.
AC ammeter/voltmeter error is comparatively low if the indicator operates using movable iron core or approximate
effective value rectifications. However, please note that the internal parts of movable iron core indicators generate
heat when a harmonic current is input, which may lead to deformation or scorching of the casing. For this reason,
use a carrier frequency of 5kHz or less for inverter circuits.
Use a power factor meter for unbalanced loads if the 3-phase load is unbalanced
Power factor meter errors may occur if the load of a balanced circuit becomes unbalanced. Select a power factor
meter for unbalanced loads if it is possible that the 3-phase load will be unbalanced.
Error may occur due to extremely low input current
Power factor meter errors may occur if the input current is significantly lower than the rated current.
When selecting the rated primary current of a CT, ensure that the secondary current during actual use will be 1/5 or
more of the rated secondary current of the CT.
Malfunction may occur due to decrease of input voltage
Wattmeters or varmeters may malfunction if the input voltage decreases. Ensure that the input voltage does not
decrease to 85% or less of the indicator’s rated voltage.
Use a special specification product in an environment with high
temperature, high humidity, or corrosive gas
Insulation degradation or failure may occur when the product is used under an environment with high temperature,
high humidity, or corrosive gas (e.g., in a wastewater treatment plant, sewage treatment plant, chemical plant,
rubber manufacturing plant).
Please select a model with special specifications such as anti-corrosion or moisture-proof treatment.
Special specification products
Please specify the necessary specifications or contact a Mitsubishi Electric representative if you require a special-
specification model (see p.10).
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