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Factory Automation


Factory Automation

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  • No : 21440
  • Release Date : 2018/08/22 16:27
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Inverter input current

An ammeter is attached to the input side of the inverter and 90 A is shown during 60 Hz operation.
The load current is shown as 65 A on the clamp meter and 67 A on the inverter.
It seems that the ammeter indication value is higher on the input side. What ratio of this to the load current?  
Is it related to the power supply capacity?
The load is a 200 V, 22 kW pump, and an ammeter (YS-8AA) and CT (CW-5L) are used.
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Since the input current has a distorted waveform and the waveform ratio is low, the total inverter input power factor is very poor depending on the power supply voltage and load factor, and is 75 to 80% for a regular inverter.
The input current (effective value) grows accordingly.

If the power supply voltage is imbalanced, the current value may greatly differ depending on the phase measured.
It is recommended to check if the current values of phases are balanced.
If the power supply voltage is imbalanced, you can improve it by installing the power factor improving AC reactor.

The input current can be calculated as "Inverter input current I = Power supply capacity [KVA]/√3?V [A]".

By connecting a power factor improving reactor to the inverter, the current waveform is cleaned and the power factor is improved. Also, the effective value of the input current is reduced.
Product Name
Inverter, magnet motor drive
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