Preventive Maintenance


EMA regularly provides preventive maintenance primarily on medium voltage VFDs.

We know what common failure points are, and can assist you in prevention.

Medium Voltage VFDs can experience catastrophic failures if not  properly maintained.  Bus capacitor failures, power supply deterioration, heat damage from improper cooling, dirt, loose connections, and maladjusted drives are just a few items we routinely find during a medium voltage VFD PM.

Our trained technicians will attempt to spot potential problems and recommend corrective action before a failure causes unscheduled and costly downtime.

What’s Involved in Routine Preventive Maintenance

Clean the drive equipment:

Dust and other foreign materials can create cooling problems, hide damaged components, cause corrosion, and cause arcing and other damage.

Check motor resistance, connections and current balance.

Motors often exhibit changes  prior to failing.

Verify all power connections:

Power connections can loosen over time due to vibration and heat related expansion and contraction. Loose power connections can cause fuse blowing, breaker tripping, damage to terminal strips, insulation failure and ground faults.

Bus Capacitors: 

Bus capacitors do deteriorate over time, and after a number of years should be replaced.  Their life is shortened from excessive heat, and other issues.  Bus capacitor failure in a medium voltage drive can lead to significant damage causing major expense and downtime.

Verify power supplies for tolerance:

Power supplies can drift out of tolerance due to electronic problems such as faulty electrolytic caps. These will eventually cause a complete shutdown.

Observe relevant wave forms for best operation:

We typically look at the supplies, at the output waveforms, at the reference signals, and at feedback signals. This often uncovers otherwise hidden problems.

Verify signal wiring, shielding properly terminated, and tight connections:

Improper shielding can cause erratic and intermittent behavior of drive equipment, and loose signal wiring is a primary cause of drive equipment downtime.