Archives for November 2018

Motor Space Heaters

Depending on the environment and criticality of your electric motor, space heaters should be strongly considered if you want to ensure maximum reliability and expected motor life. When a motor is secured (de-energized) there is an initial increase in temperature due to the loss of cooling air. However, very quickly after shutdown the temperature of the motor windings will start to drop. Once the temperature falls below the dew point, air moisture will condensate on the windings and machined surfaces creating a conductive path for current to ground. This drop in resistance to ground due to the surface moisture contamination can cause a low state of reliability for the next startup and increase the chance of a failure. When selecting a space heater, a simple calculation can give you a ball park estimate for power requirements to remain above the dew point.

H = DL/35

Where:

H = Heater size in kW

D = Diameter in Feet

L = Length in Feet (between end bell centers)

To see the results of excessive moisture on a 2000HP electric motor visit the PdMA YouTube Channel at:

https://www.youtube.com/watch?v=9SG3lNm8u8w

Annual Decatur Industrial Electric March Reliability Summit

Two Classes Offered! Take ONE or BOTH!

Above NEMA Motor 101 and DC Motor 101

Click here to download the full class flyer.

When: Thursday, March 21, 2019
Where: Decatur Industrial Electric, 1650 E. Garfield Ave, Decatur, IL 62526
Time: 8:30 AM to Noon* CST
1:00 PM to 4:30 PM * CST
Cost: FREE! Lunch provided.

*If only taking one class make sure and indicate which class and time frame you are choosing. Depending on final numbers we may have to move some people who signed up for a morning class to an afternoon class or vice versa.

Preventative Maintenance Discovers Issue Before It Causes Downtime Decatur Industrial Field Service Team Finds Brush Shunt Abrasion

Many customers use Decatur Industrial Electric for in-plant preventative maintenance (PM). It is essential to perform internal PM’s on DC, synchronous, and large electric motors as a part of managing facility assets because they have a huge impact on productivity and profit.

During a recent PM job at a customer site, our field service technician discovered brush shunt abrasion on a 750HP DC motor due to the brush shunt leads being too short and rubbing against the springs. Based on this finding, we proactively made a suggestion to add length to the brush shunts. They would go from a 4” shunt length to a 6”.

This simple fix cost the customer 94 cents more per brush. There are 6 rows of brushes at 4 per row, so 24 brushes cost $22.56, versus potentially:

At minimum reconditioning the motor would have cost $23,500
Or possibly leading to a rewinding the armature/recondition the fields at fields $48,700

Here is an example of the proper location of the shunt termination in relationship to the brush in the holder. This prevents the shunts from abrading on the brush spring coil edges.

Questions from Customers

“It’s 200 HP, why can’t you repair it?”

We get this question quite often. Yes, we can fix it…it’s just not economical to do so when something runs to catastrophic failure causing tremendous damage. New shaft, damaged core laminations, rewind, etc…

When equipment runs to complete failure, the total cost of ownership goes up due to unplanned emergency maintenance, excessive repair/replacement costs, downtime, and of course, safety. Ask our team how we can help take care of your assets to extend equipment life and reliability. Let’s get rid of motor killers and win the war against downtime!