text: A 755TR can be employed to both allow for sophisticated stop control while also accommodating elevated voltage levels. Furthermore, the active front end technology found in the 755T series removes the harmonics produced by the drive, possibly eliminating the need for PFCC’s.
  When using a dynamic brake resistor, attention should be paid to power line rises. Sustained voltage increases can lead to dynamic brakes miss-firing and overheating. This circumstance can often require the use of a larger than anticipated dynamic brake.
  At 480VAC, Drive DC Bus Voltage is around 675VDC. When the power system reaches 525-530VAC sustained, the drive’s DC bus voltage reaches 750VDC. The attached dynamic brake transistors/external choppers fire at 750VDC. The brake resistor is, therefore, being exercised during the entirety of the elevated voltage levels. Transistors, choppers & resistors must be sized for a 100% duty cycle in circumstances such as this or other steps that should be taken to prevent this occurrence.