Largo, Florida – February 13, 2019 – Join Beckwith Electric at the PCIC Middle East Conference in Abu Dhabi.
- PCIC Middle East
- February 26-27, 2019
- InterContinental Hotel
- Abu Dhabi, UAE
Learn about increasing motor life and process continuity at the following Beckwith Technical Session at PCIC.
- Motor Bus Transfer Applications Issues and Considerations
- Tuesday, February 26, 2019
- 10:30 AM-Noon
- InterContinental Hotel, Abu Dhabi, UAE
- Presenter: Tom Beckwith, Beckwith Electric CEO
This PCIC Technical Session will explore the following research:
- Residual Voltage Transfers always thought to be safe even if completed out-of-phase, can cause significant torques on motors, exceeding a 3-phase fault at the motor terminals.
- IEEE C37.96 identifies events that occur or conditions that exist prior to and during transfer where, at transfer initiate, the initial phase angle may be no where near zero!
- So at the end of a Residual Voltage Transfer spin down, the close phase angle may be nowhere near zero!
- Research with modeling motors during transfer has proven that in 40% of the cases closing at varied angles, the peak-to-peak torques developed during the Residual Voltage Transfer are higher than the 3-Phase Short Circuit Torques of the motors on the bus.
- This research has revealed that the peak currents in motors during Residual Voltage Transfers are higher than the 3-Phase Short Circuit Currents in more than 60% of these cases.
- This motor modeling research also shows that in 89% of the cases closing at varied angles, the currents during Residual Voltage Transfer are in excess of six times rated current.
- Synchronous In-Phase Transfers may take longer than some arbitrary time limit. Depending on the initial phase angle at transfer initiate, it may take more than 6 or 10 cycles for the motors to rotate back into synchronism.
- Compared to blind Residual Voltage Transfers, these Synchronous In-Phase Transfers are much faster, closing at much higher voltages, at much lower slip frequencies, with closure near zero degrees and low inrush current and torque.
- The 1.33 resultant pu V/Hz transfer criterion in NEMA MG-1, ANSI/NEMA C50.41 and IEEE C37.96 has no correlation to motor torque and actually gives passing grades to severely excessive torques upon transfer.
- Time period transfer criteria, stated in NEMA MG-1, IEEE 666, ANSI/NEMA C50.41 and IEEE C37.96, are arbitrary and would permit severely out-of-phase transfers or conversely may preclude perfectly good synchronous transfers.
- A Motor Torque Ratio TPK /TL, introduced as the aggregate peak torque at transfer expressed as a multiple of the aggregate load torque prior to transfer, displays a high correlation to the phase angle at transfer with little effect from voltage or frequency difference.
- If it is torque that reduces the life expectancy and damages motors or driven equipment, or both, as suggested in the C50.41 Standard, then the industry must use a torque-based criterion to assess if transfers are being completed within acceptable torque limits.
Learn more at www.beckwithelectric.com/events/pcic-middle-east/
About Beckwith Electric
Beckwith Electric, founded in 1967, is a premier provider of innovative and high quality products, technical services and solutions that meet the needs of customers involved in the production, transmission, and distribution of electric power. Starting in a garage outside of Chicago, IL, the company relocated its headquarters to Largo, FL, in 1972 and now serves customers worldwide. The company is incorporated in the United States and all of its products are proudly engineered and manufactured at its headquarters in Largo.
Beckwith creates solutions that protect power systems around the world. Beckwith’s field-proven smart distribution automation controls for transformers, regulators and capacitor banks incorporate unique control strategies, advanced microprocessor architecture and cyber security compliant communications. Power systems protection solutions include generator, transformer, feeder, recloser and distributed energy resources. Additionally, Beckwith’s fast motor bus transfer systems provide continuous, reliable motor protection, working to preserve process reliability. Beckwith also offers advanced synchronization systems for the automatic synchronizing of a generator with the best accuracy in the industry to assure safety for your most expensive asset.
Beckwith Electric’s customers include power utilities, heavy industrial and large institutional markets, and their consultants. Much of Beckwith’s success comes from listening to customer feedback and using that information to influence the design features of its products. Even with over 25 patents, our core principal continues to be “Products defined by you, refined by Beckwith.”
For more information, contact:
Beckwith Electric Communications