AC Mitsubishi S-N50:- How to Check for Worn Electrical Contacts

Video Transcript:

Electrical Contacts and Contactor Inspection

Featuring AC Mitsubishi S-N50 contactor
 
Proper equipment maintenance is always necessary, but especially in the lift industry.  Whether you’re lifting people in elevators or moving containers at the dock, regular, qualified maintenance is essential.

In this video we’re going to look at how you can check the wear of electrical contacts to help determine if they need to be adjusted or changed.

The contactor we’re using for illustration purposes is not connected to a power source.

If you’re checking a contactor that is operational and connected to a power source, please follow all safety precautions including:

• Turning off all power to the unit you’re inspecting
• Wear protective fire or flame resistant, known as FR, clothing
• And check that your work environment is clean, stable and electrically safe

 

AC Mitsubishi S-N50 Contactor Inspection

We’re going to look at an AC Mitsubishi S-N50 contactor commonly found in the elevator industry.  First, do a visual check of the contacts to determine if they’re worn, burnt or contaminated by any environmental substances.

Contactors are designed to be normally open or normally closed.  This unit is NO or normally open.  You can push down on the movable contact holder to check the alignment as it mates with the stationary contacts. 

There should be as much contact as possible.  Sometimes the contact pads are crowned or have a radius like this contact. This is not a concern as long as the alignment is good.  If misaligned, the contact alignment should be adjusted according to the manufacturer’s instructions.

Next, check the pads for pitting or other wear that could cause electrical arcing.  Here are a few examples of pitted and burned contacts. Arcing can cause the movable and stationary contacts to weld together creating a dangerous condition.  If pitting or burning is discovered, then the contacts should be changed by a licensed electrician following the manufacturer’s instructions.
 

Replacing Electrical Contactors

Finally, you can check the spring tension and replace as needed.

If your contacts need to be replaced, Repco’s large inventory is as close as your computer and just a phone call away.  Repco stocks replacements for this Mitsubishi contactor series and for many other control manufacturer’s products used in the lift industry.

For more information about Repco replacement contacts and contact kits, please search www.repcoinc.com on the web or Call 800-822-9190.
 
Related Links:
Mitsubishi Electrical Contacts