Successful Motor Protection Formulae

As we have discussed before, all overload relays have one major limitation - because they operate on line current, they do not directly sense the motor temperatures.

However, with proper heater selection and careful attention to the factors that affect heater performance, the overload relay can work extremely well to protect the motors.

Some of these factors that need close attention are:

Motor full load current
Motor temperature rise rating
Service factor
Ambient temperature at the motor and at the protector
Motor locked rotor current ratio
Starting time
Duty cycle
Locked rotor endurance time.

If attention is not given to these factors, the overload relay will perform poorly. The other factor to be considered is maintenance. Below are some maintenance routines:

Cleaning - The overload relays should be cleaned periodically. Dirt or dust created by the operating conditions in the plant tends to settle around the moving parts in the device and prevent it from operating properly.

Tightening connections - Because most overload relays make use of current flowing through heater elements to sense overloaded conditions, it is important that the electrical terminals are not loose. Loose electrical connections can create extra heat and cause false tripping of the relays.

Inspecting heater size - Heaters can oxidize over a period of time and become smaller in cross section. The smaller current flowing in the smaller heater generates the same amount of heat to cause unnecessary tripping of the relay.

With careful selection and maintenance, overload relays are excellent for motor protection.

The wide use of thermal overload relays in industry attests to their acceptance as the most practical means of protecting motors from overloads. And they are the most economical solution available.

Until next time...

"Looking For Magic Gadgets Discount?" Gifts for Curious Minds expands Our Thinking! Will it Spark the Genius in You?

Many years of working experience in Marine, Facilities, Construction has given the author material for writing e-books and articles related to engineering, and management. Subscribe to facworld ezine More information at Marine Engineer and M & E Engineer

Architect or Building Designer ? Who Do You Choose?

Thinking of building a new home or complex? Will you... Read More

Installing a Home Theater System

Thinking about installing a home theater system? You're not alone.... Read More

Imported Tools vs. Brand Name - Are They As Good?

So you are looking for hand or power tools on... Read More

Useful Home Products Will Help Your House Sale Profits

Even if you've never been involved in the sale of... Read More

Bathroom Remodel - The Plan

Planning a bathroom remodel? Each home project of this nature... Read More

Get Your Home Ready To Sell

Have you been considering selling your home in the near... Read More

Why Hardwood Flooring is a Good Investment

Hardwood flooring has a timeless air of qualityHardwood floors have... Read More

Do You Have a Master Bedroom? You Shouldnt! Tips for Remodeling Your Bedroom

The word "master" is an antiquated term that suggests control,... Read More

Mommy, Mommy, Theres a Caterpillar on my Bed

Chenille has been used for bedspreads since Catherine Evans revived... Read More

Beat the Summer Heat - What Size A/C Do I Need?

A larger air conditioner will not always provide more cooling.... Read More

So You?ve Put an Offer on a Home. What?s Next?

You've finally found the home of your dreams, 3 bedrooms,... Read More

Making a Pen with Your New Wood Lathe

So you just purchased a wood lathe but do not... Read More

Keep Your Home Happier

It turns out your mother was right after all --... Read More

The Advantages of Pre-Engineered Steel Buildings

Steel is a remarkable material that has been steadily increasing... Read More

Seeing the Light

Lighting"Light has illuminated the path of humanity" ? While Einstein... Read More

Buyers Guide For Modern Mailboxes

Modern mailboxes are made predominately from cast aluminum or stainless... Read More

Brighten Up Your Shelves With Picture Frames

Would you like to add a personal touch to your... Read More

Protecting Yourself from Miter Saw Hazards

A miter saw, also known as a "chop saw," is... Read More

Mistakes?

MISTAKES.Don't worry about making mistakes. Everyone makes mistakes. Why should... Read More

When Is It Time To Call The Professional?

For most Do-It-Yourself (DIY) home project managers, the most difficult... Read More

Chiminea ? Buy It for the Versatility of Enjoying Both Fireplace and Grill!

I recently visited friends who served me a dinner of... Read More

Hot Tubs Create a Backyard Oasis

What would you like in the backyard that is great... Read More

Wallpaper Doesnt Just Cover...It Defines The Room

Wallpaper is often overlooked as a key part of an... Read More

Easy To Follow Tips For Keeping Energy Costs Down

When it comes to cooling our homes and businesses, the... Read More

Quick and Dirty Guide to Wood Flooring

If you've always longed for hardwood floors, you're in good... Read More