Severe Residual Voltage Motor Bus Transfer Torques
#Seminars
| ANSI C50.41 states, “Induction motors are inherently capable of developing transient current and torque considerably in excess of rated current and torque when exposed to out-of-phase bus transfer” with the magnitude of transient current and torque ranging from 2 to 20 times rated. Since a motor bus is an aggregate of different motors and loads, it’s unrealistic to create an industry criterion for the transfer of the aggregate bus based on individual motor rated torques. Data from motor bus transfer events at industrial facilities were analyzed with a transfer metric, based on the ratio of the aggregate peak torque at transfer to the aggregate running load torque prior to transfer. These results were then compared with the C50.41 torque range from 2 (good) to 20 (bad) times rated, and per unit Volts/Hertz criterion, calculated at the instant of transfer presently used to determine an acceptable transfer. To calculate the aggregate motor torques before and at transfer, time domain oscillographic samples of voltage and current signals are used to calculate the real power drawn by the motors. Induction motor air gap torque is air gap power divided by synchronous speed. Analyzing field cases, calculating Torque Ratio and comparing with the per-unit Volts/Hertz value, demonstrate the validity of this Torque Ratio metric for determining an acceptable limit for transfer. |
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- Date: 17 Oct 2017
- Time: 06:00 PM to 08:30 PM
- All times are (GMT-06:00) US/Central
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- Jacobs Engineering, Tower Two
- 5985 Rogerdale Road
- Houston, TX. 77072, Texas
- United States
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http://sites.ieee.org/houston/
- Starts 08 October 2017 12:00 AM
- Ends 18 October 2017 12:00 AM
- All times are (GMT-06:00) US/Central
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