Best practice for large electric motors

In summary, the person is asking for advice on whether it is more cost effective to shut down or leave running the electric motors in their manufacturing company during breaks and lunch. They also inquire about the effectiveness of using "phase aligners" to improve motor efficiency and the possible need for a capacitor bank to correct a bad power factor. They are directed to check their bill for any indication of a bad power factor.
  • #1
justaguywa?
2
0
This may not be the place to ask this question, but I can't seem to get a good answer anywhere else...I have a manufacturing company. I am on a 3-phase demand meter. I'm trying to figure out if it is more cost effective to shut all the electric motors down during breaks and lunch and restart or just leave them running "idling" during these times? The motors are 2 - 100 HP, 4 - 75 HP, and 4 - 50 HP.

The other question I have is about motor efficiency - I've had a salesman come by and talk to be about "phase aligners" (Don't really know what they are, but I'm guessing some sort of capacitor that "cleans up" the inbound electricity). Anyone know anything about these and if they are worth fooling with?
 
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  • #2
For the first question, it depends a little on what these motors are doing, but if they are fully loaded but doing something unnecessary, they are consuming a lot of energy that could be saved. About $60 per lunch hour.

For the second, there are some products that advertise various power cleaning capabilities. I tested one once on a compressor and it didn't seem to do much. What you do really want to make sure of, though, is that your power factor isn't bad enough that the electric company charges you for it (it should be clear on your bill). If it is bad, you should have an engineer select and a contractor install a capacitor bank to correct it.

Welcome to PF - there's no better place for such a question!
 
  • #3
Thanks for the response.

The motors are not loaded during these times - I thought it would be better to shut them down, but the practice has always been to leave them running - someone told a previous supervisor that because of the demand meter, it was better just to leave them running than to restart them after breaks (15 minutes X 2) and lunch (30 minutes). Each motor is started independant of the other, so it's not like they are all restarting at once.

You say that there should be something on my bill if the power factor is bad? Where should I look for that. I'm sure every power companies bill is different, but is there a certain nomenclature that would show up or stand out if I have a problem?

Again thanks for the information.
 
  • #4
For power factor, it should just say power factor, followed by a number between 0.5 and 1.0. The detail of the bill shouldn't be very long...
 

1. What is the best practice for maintaining large electric motors?

The best practice for maintaining large electric motors includes regular inspections, lubrication, and cleaning. It is also important to monitor and record the motor's temperature and vibration levels, as well as address any issues or abnormalities promptly.

2. How often should large electric motors be serviced?

The frequency of servicing large electric motors depends on their usage and operating conditions. Generally, they should be serviced at least once a year, but more frequent servicing may be necessary for motors that are used continuously or in harsh environments.

3. What type of lubricant should be used for large electric motors?

The type of lubricant used for large electric motors should be based on the manufacturer's recommendations and the motor's operating conditions. It is important to use a high-quality, electric motor-specific lubricant to ensure optimal performance and longevity of the motor.

4. How can I prolong the lifespan of a large electric motor?

To prolong the lifespan of a large electric motor, it is important to follow the manufacturer's recommended maintenance schedule, use the appropriate lubricant, and address any issues or abnormalities promptly. It is also important to avoid overloading the motor and to ensure proper ventilation and cooling.

5. What are the signs that a large electric motor needs to be replaced?

Signs that a large electric motor may need to be replaced include excessive noise, excessive heat, abnormal vibrations, and decreased performance. It is important to address these issues promptly and consult with a professional before deciding to replace the motor.

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