Selecting a Drive

International English

Supplies at the end of long power lines in remote areas can rise excessively in the evening and weekends when large loads are no longer present.

Industries with locally controlled and generated supplies can have poor regulation and control.

Power systems in certain parts of the world may not meet expected tolerances.

In all installations, check that the supply will remain within the tolerances stated above. Operation outside of the stated supply levels will probably cause damage.

3.2.2Supply Disturbance

Many supplies are well controlled and remain in tolerance, but are affected by local disturbances. These can cause faulty operation and damage to inverters. In particular, check for:

·Power Factor Correction equipment. Unsuppressed switching of capacitor banks can produce very large voltage transients and is a common cause of inverter damage.

·High power welding equipment, especially resistance and RF welders.

·Other drives (in particular large, old DC drives), semiconductor heater controllers etc.

Note.

Inverters are designed to absorb high levels of supply disturbance. Voltage spikes up to 4 kV for instance. However, the above equipment can cause power supply disturbances in excess of this. It will be necessary to suppress this interference - preferably at source - or at least by the installation of an input choke in the inverter supply. EMC filters do not suppress disturbances with this level of energy; over voltage protection products such as metal oxide varistors should be considered.

Damage can also be caused by local supply faults and the effects of electrical storms. In areas where these are expected, similar precautions are recommended.

Power Factor

Correction

Equipment

Welders

RF Heaters etc.

Large Drives and

Power Electronic

Systems

Lightning, Power System Faults

MICROMASTER

Motor

Add input inductor and

Over Voltage Protection

Equipment here.

Figure 3-1 Sources of Supply Disturbance

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MICROMASTER Applications Handbook