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
For most Do-It-Yourself (DIY) home project managers, the most difficult... Read More
Many of us avoid home improvement projects due to their... Read More
1. What experience does your contractor have with this type... Read More
As we become more of a home-based society, many more... Read More
When you are choosing a color scheme for any room... Read More
My favourite episode of Bugs Bunny is the one where... Read More
Refinishing your hardwood floors yourself can be time consuming and... Read More
A shower curtain can add the perfect touch to any... Read More
Interior remodeling can have an amazing impact on the look... Read More
What is the absolute best way to clean carpet? Carpet... Read More
Even though most of the houses are well lighted with... Read More
Everyone wants to save money. Don't you? Well, painting your... Read More
When double glazing first became a popular window choice in... Read More
Fixing Old Wooden ChairsIF you have some old chairs that... Read More
Purchasing a hot tub is a big investment and one... Read More
All of us live in houses but how many of... Read More
Motion detectors are in use all around us in both... Read More
Tax season is over...The spring holidays have passed... Hopefully by... Read More
Do you have embarrassing gas problems? Do you find this... Read More
Why should you even consider sealing your asphalt driveway?Seal your... Read More
It doesn't matter if you live in a hot climate... Read More
Window coverings serve an important role in your home, giving... Read More
There are some things to consider when creating plans for... Read More
In the last five years a new type of clear... Read More
Purchasing an air purifier can be confusing, and you do... Read More
So you just purchased a wood lathe but do not... Read More
The cost of furnishing a conservatory can catch many people... Read More
So you're building the bath of your dreams but find... Read More
Even if you undertook the task of building your own... Read More
You're told to take vitamins, drink plenty of water, get... Read More
Selection of bedstead is also an important thing as selection... Read More
The last thing you would think about when you are... Read More
Any advice or guide on the interior design of a... Read More
All of us live in houses but how many of... Read More
So it's too humid in your 10' X 10' bedroom.... Read More
Last week I told you how to measure your wood... Read More
It started with my need for a new mixer. OK.... Read More
Even though most of the houses are well lighted with... Read More
Hardwood floor styles come in strips, planks and parquet, and... Read More
Last year, we bought this big ol' 1887 house. We... Read More
Installing a pre-cast concrete stairway to your home's basement is... Read More
Hiring a professional to replace your rollers could cost you... Read More
Why replace your single-glazed windows with double glazing ? For... Read More
How many of you have experienced this situation? As the... Read More
Designing Your Own Dream Home for the New Home Builder:... Read More
Don't you just love the design of some of these... Read More
Is your home décor lacking that extra something that spells... Read More
Ceramic Tile brings a texture, richness and color to a... Read More
Housing and smart houses. I believe that we could have... Read More
Most conversion works to an existing structure is often more... Read More
Home Improvement Home Improvement |
|
| العاب | منتديات هيدى | الزاوية الحمراء | |
|
Pharaohs products egypt products Egypt shopping Shopping in Egypt sho Egypt Bazaar Pharaohs Shoping Center Egypt Pharaohs |