Delta Electronics VFD-EL User Manual

Chapter 5 Troubleshooting| 

Revision August 2008, 2ELE, V1.02 

5-9

Many sources of noise surround AC motor drives and penetrate it by radiation or conduction. It may 

cause malfunctioning of the control circuits and even damage the AC motor drive. Of course, there 

are solutions to increase the noise tolerance of an AC motor drive. But this has its limits. Therefore, 

solving it from the outside as follows will be the best. 

1. 

Add surge suppressor on the relays and contacts to suppress switching surges.  

2. 

Shorten the wiring length of the control circuit or serial communication and keep them 

separated from the power circuit wiring. 

3. 

Comply with the wiring regulations by using shielded wires and isolation amplifiers for 

long length. 

4. 

The grounding terminal should comply with the local regulations and be grounded 

independently, i.e. not to have common ground with electric welding machines and other 

power equipment. 

5. 

Connect a noise filter at the mains input terminal of the AC motor drive to filter noise from 

the power circuit. VFD-EL can have a built-in filter as option. 

 

In short, solutions for electromagnetic noise exist of “no product”(disconnect disturbing equipment), 

“no spread”(limit emission for disturbing equipment) and “no receive”(enhance immunity). 

Since the AC motor drive is an electronic device, you should comply with the environmental 

conditions. Here are some remedial measures if necessary. 

1. 

To prevent vibration, the use of anti-vibration dampers is the last choice. Vibrations must 

be within the specification. Vibration causes mechanical stress and it should not occur 

frequently, continuously or repeatedly to prevent damage to the AC motor drive.  

2. 

Store the AC motor drive in a clean and dry location, free from corrosive fumes/dust to 

prevent corrosion and poor contacts. Poor insulation in a humid location can cause short-

circuits.  If necessary, install the AC motor drive in a dust-proof and painted enclosure and 

in particular situations, use a completely sealed enclosure. 

3. 

The ambient temperature should be within the specification. Too high or too low 

temperature will affect the lifetime and reliability. For semiconductor components, damage 

will occur once any specification is out of range. Therefore, it is necessary to periodically 

check air quality and the cooling fan and provide extra cooling of necessary. In addition, 

the microcomputer may not work in extremely low temperatures, making cabinet heating 

necessary.