In this article, we will discuss the effect of humidity and moisture on an electric motor.
Some Common Factors That Seriously Affect Motors
An electric motor is commonly used in almost all electrical applications. And almost every electrical device is incomplete without an electric motor.
The operational environment of the electric motors may vary, We can say that there are motors working in all workplace environments. These environments like:
- Wet locations.
- Rainy outdoors.
- Hot locations.
- Dusty locations.
This makes the chance for multiple factors to cause a failure of the electric motors. Some common factors are:
- High motor temperatures and overheating
- Dirt and contaminants
- Overcurrent and overvoltage.
- Moisture and humidity
- Water ingress.
The above are the most common reasons that can cause a motor failure.
What Happens, If An Electric Motor Gets Wet?
A complete damage is the worst scenario when a motor gets wet. It happens due to the insulation breakdown, and then a short circuit.
This Image is for a synchronous generator in my work. As you can see it is completely damaged, and we should do very hard work to make it work again, We should rewind new windings for it.
You should expect the reason of this damage, It is of course humidity and foggy weather. Our work is in the desert, some days it becomes very foggy.
Some of our electric equipment IP ratings are not high enough to protect it from fog and humidity.
Water, moisture, or humidity significantly affect the performance of electric motors. It can cause corrosion to the shaft, bearings, windings, motor enclosure and rotors.
Sometimes moisture enters into the windings of the electric motor. Which can cause motor failure by causing a short circuit. It is important to keep the motor place covered.
Similarly, if the corrosion occurred at the maximum level, there is a chance of motor breakdown.
To protect motors from moisture in large motors, we use one of the two methods below:
Condensation heaters for outdoor usage. Sometimes it is referred to as space heaters.
It keeps the internal temperature of the motor above the ambient dew point when the motor is off. The heater is interlocked with the motor control circuit to work only when the motor stops.
Besides this, the heater also protects condensation inside the electrical winding and rotating part of the motor.
Typical applications of space heaters are all types of motors that are used in wet conditions. For examples shipboard and marine equipment, offshore, well pumps, dockside cranes and of course in the desert weather, like the place of my work where fog destroys many of our electric equipment every year.
For more details about space heater, Read my other article here.
An other practical option to prevent condensation is Trickle Heating, In this method we apply a very small voltage to the motor winding while it is no working. The current passing through the windings produce enough heat to protect the motor from moisture and humidity.
You may ask, If its very risky to install electric motors in wet locations, What about outdoors applications? Can’t we install any electric motors outside?
This is a very practical question, Let’s do deep to answer it.
Which Motor IP Rating Is Suitable For Outdoors Rainy Locations?
As a short answer, the most favorable and perfect motor for outdoor usage is IP65, IF66, and IP 67.
But I highly recommend reading to the end, as I will explain how to choose the better IP rather than the higher one. Now let’s understand the protection against liquids.
Ingress protection is a standard for an electric equipment to protect it against environmental conditions like dust and water.
The IP number consists of two numbers. The first number defines resistance to dust and the second number defines resistance to water.
The IP rating starts from IP20 to IP 68. To know more about the motor resistivity to dust and water please check out the following table.
|S.No||IP Rating||Object Protection||Water Protection|
|1.||IP20||Offer protection from Solid objects over 12.5mm||Does not offer protection from water|
|2.||IP23||Offer protection from Solid objects over 12.5mm||Spray at an angle up to 60° Vertical|
|3.||IP24||Offer protection from Solid objects over 12.5mm||Offer protection against Splashed water|
|4.||IP44||Offer protection from Solid objects over 1mm||Offer protection against Splashed water from any side|
|5.||IP54||Offer protection against dust||Water splashed against the machine from any direction shall have no harmful effect.|
|6.||IP55||Offer protection against dust||Water projected by a nozzle against the enclosure from any direction shall have no harmful effect.|
|IP56||Offer protection against All types of dust||Water from heavy seas or water projected from jets shall not enter the machine in any harmful quantity|
|7.||IP65||Offer protection and excluded from All types of dust||Water projected by a nozzle against the machine from any direction shall have no harmful effect.|
|IP 66||Complete protection against live moving objects and dust||Water from heavy seas or water projected from jets shall not enter the machine in any harmful quantity|
|8.||IP68||Offer protection and excluded from all types of dust||All types of tight water sources|
So from the chart mentioned above motors IP protection depends mainly on the weather or environment conditions.
In some cases rain falls almost vertical with very low pressure. In this case a motor with IPX3 should work with no water ingress issues.
So, its better to check the location of installation before ordering the motor, you can check weather and rain to make the correct choice.
Which Motors Are Suitable For Wet Locations?
As mentioned above, wet locations have a high amount of humidity. Which can enter into an electric motor and cause corrosion to different parts of the motor.
Besides this humidity enters the windings of the motor causing breakdown. Choosing the right type of motor for a wet location is a hard job.
However, we suggest installing those types of motors in wet locations. Those motors which are completely covered and water or humidity cannot go through them.
Different types of motors that are suitable for wet locations are:
- Totally Enclosed Fan Cooled Motor (TEFC)
- Totally Enclosed Non ventilated Motor (TENV)
- Totally Enclosed Wash Down (TEWD)
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