Motor Bearing & Bearing House Temperature Limit As Per Standard?

I can't answer that, but I'm sure anyone trying to will want to know more details. What type of equipment, what kind of bearing, etc.

I suspect the bearing manufacturer will have something to say about this.

Yes there is a standard.

As you haven't given any details it's a bit of a rough guess.

"If smoke comes out of the bearing housing! It's too hot!"

tigerdon-

Yes and No. Most motor manufacturers put a temperature limit on the name plate for a particular motor. It usually is the max temperature for the whole motor operation. Since the bearings and bearing casing are so close and in intimate contact with the motor frame it is acceptable to consider them as being at the same temperature. That's the Yes.

No, there are no standards specifying the temperature limit for motor bearings and bearing casings for any group of similar or identical motors. Most motors have standard frames based on published specifications. This is not true for the temperatures of similar sized motors.

As a rule of thumb, and I realize some of us have ten of them, I personally used my own standards. If the bearing is easy to touch with no heat the motor/bearings are fine. If it is warn or hot to the touch it is running ok. If I touched it with a finger and my arm immediately jumped right away there probably is a problem with the bearing. If I touched it with a finger and the motor burned my finger with a 1st degree burn the bearing is definitely bad and I was pretty stupid for touching it instead of using a non-contact infrared thermometer. I now recommend the IR thermometer for all temperature readings of bearings instead of being stupid and touching it.

Good Luck, Old Salt

Dear Mr.Tigerdon,

The answer for your question is YES. There are standards,refer SKF BOOK. i have the detail, but it is NOT Openeing. I will try try to open and copy and post after few Hours.

DHAYANANDHAN.S

Each Manufacturer specifies the conditions and maximum operating limits, depends upon type of bearing,

Antifriction (Ball, roller etc)

or Sleeve (Babbitt metal or phosphor bronze or dry type like Teflon, graphite etc.)

For Babbitt bearings maximum limit is 90°C, in certain exceptions 95°C.

For Antifriction Bearings it depends upon Insulation Class of Motor. Now a days motors are available in Class B, Class F and Class H. Class H has maximum hot spot temperature of 175°C for winding. Temperature of frame of Class H motors is measured around 85°C. Which is quite hot. Bearing Housing temperatures of such motors are measured around 70°C, even cooler at times (depending upon ambient).

Bearings are same whether it is Class B or Class F or Class H motor. With increase in expected temperature of frame, the type of grease is changed. For example For Class F and Class H motors, recommended grease is Lithium Soap Based Grade G3 which are suitable for continuous operation up to 130°C

Also for higher class of motors, when selecting clearance of Bearing, now a days antifriction bearings manufactured to C3 clearance are selected (C3 is the highest clearance - or the bearings which are found manufactured to maximum applicable +ve Tollarance). Reason for selecting C3 is to ensure enough clearance is maintaned between balls or rollers and race for film of lubrication (grease) always ensured.

If the Asker has raised the question to set monitoring and protection unit of bearings, then it is suggested to set it slightly higher, for example if bearing is operating normally at maximum of 60°C, set alarm at 65 to 67°C so that early warning is given for any problem in the bearing.

Also it shall be noted that during greasing the temperature of bearing goes up, to 70 to 75°C. Higher and faster it will shoot up depending upon the rate and quantity of excess grease. This shall turn to normal within few hours once the excess grease is rejected.

Hence setting the warning at lower limit (as suggested above) also helps the maintenance staff that he is not overgreasing.

These specs. are as per I.S.325. (Indian Standard).

if it looks like this its too hot

if you look at this tag you'll notice the Max ambient is 40C, so this motor should not exceed 40C over the ambient air temp (air-cooled motor) with this info a non contact thermometer (IR) can take the temp of the outside of the motor and determine if it's within the manufactures limits, as to bearing specific you'd have to contact them, even if they dig up the number I don't see how you can use it other than to win a bet that you can actually find out, the "max ambient" should cover any concern about heat maximums the motor will experience.