AC & DC DRIVE

MAINTENANCE

Glenn Martin

Omron IDM Controls

•Custom AC & DC Variable Speed Controls

•Engineered Products & Systems

• Field Upgrades and Retrofits

• Electronic Control Service & Repair

Drives Division of Omron Electronics, Inc

What should you get out

of this presentation?

• How often to service drive systems

• Define a drive maintenance schedule

• How to evaluate your operating conditions

• What information drives can provide about

the equipment and the process

• How to reduce down time

What We’ll Cover

• What are contaminants

• Ambient Temperatures

• Maintenance on AC vs DC

Drives

• Problem Solving using the

Drive

Atmospheric Conditions

• Equipment enclosures typically have some type of cooling system such as fans & filters, air conditioners, ducted air, etc.

• Cooling systems are affected by contaminants and ambient temperatures.

• Performance and maintenance schedules on these systems are directly affected by the conditions in the atmosphere.

• Higher temperature and contaminant levels usually require more maintenance.

Contaminants

• Equipment enclosures typically have

some type of cooling system such as

fans & filters, air conditioners, ducted

air, etc.

• Cooling systems are affected by

contaminants and ambient

temperatures.

Cooling System

Maintenance Schedule• Check filters (air and water) on a regular

basis, change as required.

• Insure all fans are operating (this includes fans on the drives and in the enclosure)

• Inspect air conditioning equipment, and heat exchangers (air and water) often. How often depends on the level of contaminants in the area.

• Frequency of inspection will be determined

over time. Neglect = Downtime

Heat

• The life and performance of electronic

equipment is greatly reduced by

elevated temperatures

• Power electronic equipment such as AC

and DC drives produce a certain

amount of heat that must be removed

from the equipment enclosures

Heat

• If temperatures around the equipment

cabinets are high, consider ducted air or

air conditioners.

• It is best to keep temperatures inside

the equipment enclosures below 115

deg F

Key Drive Maintenance

Components

• Power Semiconductors

DC drives – Silicon Controlled Rectifiers

(SCR)

AC drives – Diode Modules,

Insulated Gate Bipolar

Transistors (IGBT),

Darlington Transistors (older

AC drives / inverters)

Key Drive Maintenance

Components

• Electrolytic Capacitors

DC Drives – Normally small circuit board

mounted devices. Check every 6 to 12

months.

Key Drive Maintenance

Components

• Electrolytic capacitors.

AC drives – large and small devices used.

Common scheduled maintenance item.

Should be inspected every 12 to 24

months. Manufacturers of AC drives used

to recommend replacement of large

capacitors every 5 years. New capacitor

technology has improved this.

Maintenance Components on

AC & DC Drives

• Power Semiconductors

Not a common scheduled maintenance

item. Should be inspected every 12 to 24

months.

• Electrolytic Capacitors

Common scheduled maintenance item.

Should be inspected every 6 to 12 months.

Symptoms

• Motor runs rough.

Could be due to an open SCR on a

dc drive or an open IGBT on an ac

inverter or servo dirve.

• Drive over current faults or blows fuses –

Could be due to a shorted SCR on a

dc drive or an open IGBT on an ac

inverter or servo dirve.

Symptoms

• AC drive over voltage or input phase

loss faults.

Could be due to stressed or weak

capacitors on an ac inverter or servo

dirve.

Who Should Perform Drive

Maintenance

• Plant electrical maintenance personnel

trained to service the specific brand /

model of AC or DC drive

• Factory service technician

• Factory authorized drive service

company

Technical Training

Certified technicians teach Operators and Maintenance Certified technicians teach Operators and Maintenance

everything from motor and control basics to AC or DC everything from motor and control basics to AC or DC

drive and motor control trouble shooting. drive and motor control trouble shooting.

HandsHands--on demo unitson demo unitsComprehensive classroom training Comprehensive classroom training

Technical Service & Support

24 hour nationwide service to

respond to emergency breakdowns

Out Source ServiceOut Source Service

Trained In House Trained In House

MaintenanceMaintenance

Preventative maintenance predict

and contain your maintenance

costs

Drives Have Valuable

Information

• Mechanical and some process related problems can be diagnosed by using information available in the drive.

• Load and speed information occurring at a driven nip can be monitored in the drive.

• Variations can be indicative of machine or process problems.

Examples of using Drive

Information

• Tension variations from a faulty idle roll

bearing may be seen as load pulsations

in a nip drive.

• Coating thickness variations can show

up as speed or load changes.

How to Plan for Efficient

Maintenance

• Proper planning for machine

maintenance can greatly reduce the

time required to perform the

maintenance task.

How to Plan for Efficient

Maintenance

• Reduce control system confusion

• Eliminate problematic older drives

• Consider replacing mechanical control

with electronic control

Why Change?

Why Change?

Old control

cabinets can

be difficult to

trouble shoot

when a break

down occurs

HMI & PLC Verses Old

Control Panel

• Reduction of control system confusion

• Improved operator interface to the

machine

• Improved trouble shooting capability

• More information available to operator

Drive Retrofit

• Eliminate Obsolete Components

• Improve Reliability

• Improve Performance

• Increase Production Capabilities

• Consistent Production Output

Drive Retrofit

BeforeBefore AfterAfter

Machine Driveshaft

Layout

• Line Shaft

• Pulleys and Belts

• Gearboxes

• Large Drive Motor

Frictional AccumulationFrictional Accumulation

Electronic Line Shaft

• Small Motors

• Lower Horse Power

• Less Moving Parts

• Reduced Wear

Improved Efficiency

• Downtime

• Maintenance Cost

• Spare Parts Stocking

• Brush Service/Maintenance

AC and DC Drive

Maintenance

Glenn Martin

Applications Engineering Manager

(713)849-1900

glenn.martin@idmcontrols.Com

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