We covered the entire range of use from data management, data input, testing, and interpretation of test results using the AWA instrument.
Every dollar saved truly makes a difference in today’s environment. However, when we can help put a $1 million dollar figure in front of a savings, it’s news worth sharing.
Decatur Industrial offered to provide training on the SKF Baker AWA (Automated Winding Analyzer) beyond what the manufacture offered. The training would be provided to the customers’ electricians responsible for medium-voltage machines (up to 4,000HP) and technicians responsible for low-voltages machines prior to their upcoming outage. Critical motors would need to be analyzed with the SKF Baker AWA for service acceptance. We held true “hands-on” training with the assistance of the customer supplying several motors from their warehouse.
In the process of testing, we discovered two issues:
- A 4000 HP motor failed insulation resistance to ground and the Polarization Index (PI) test, indicating that moisture may be an issue.
- A Coal Mill motor was found to have an out of range Pulse –to- Pulse Error Ratio on the SKF Baker AWA. This indicated that the motor had a defect in the turn-to-turn insulation of the coil wires. (Not a Decatur Industrial rebuild!)
What Happened Next:
- 4000 HP Motor: They were able to dry the moisture from the windings with space heaters to obtain a satisfactory insulation resistance with the SKF Baker AWA instrument training we provided.
- Coal Mill Motor: Sent to D.I.E. repair shop for a rush rewind and repair which we were able to accomplish within their outage. With our focus on solutions based reliability, we suggested and made improvements over the OEM winding design.
- Uprate winding – remove excess slot filler and redesign the coils to provide an 8% copper increase
- Implemented state of the art corona protection in the stator coils.
Our thorough evaluation of the motor also found mechanical issues. This resulted in machining and repair of both bearing outside diameters to properly OEM bearing-to-housing machine tolerances.
Calculated Total Cost of Ownership Savings:
4000 HP Motor
It could have experienced an immediate failure or a potentially irreversible ground insulation degradation if put into service – both resulting in unplanned downtime and emergency maintenance!
Coal Mill
- $8,000 – $16,000 per day (depending on prices and load demand)
- PA Fan – $25,000 – $50,000 per day
- Plus labor rebuild costs
Coal Mill: $168,000 to $336,000 plus motor repair
PA Fan: $525,000 to $1,050,000 plus the motor repair