Regeneration occurs in an AC variable frequency drive system when the load overhauls the motor. This can occur when trying to decelerate the load, or when some external force causes the motor to overhaul and act like a generator. The energy contained in the rotating equipment flows into the drive, and is manifested as increased DC bus voltage in the inverter. This over voltage is traditionally wasted as heat by means of dynamic braking resistors.
These basic seal system considerations can significantly reduce the energy footprint of the seal face interaction. Their contribution to the overall sealing system energy footprint should be considered after review of all the components of the sealing system's energy footprint.
Paddle wheel flow sensors not only continue to remain strong in industrial applications, their use is growing. Because these devices offer the lowest cost per sensing point of any flow measurement technology, users can save significantly on purchase, installation and maintenance costs.
When it comes to pressure and flow, variable speed pumping applications can be divided into three basic categories. Constant pressure-variable flow (Cp-Vf) attempts to keep pressure relatively constant over a range of flows. Constant flow-variable pressure (Cf-Vp) tries to achieve the opposite by using varying pressure to keep flow constant. Variable pressure-variable flow (Vp-Vf) applications can accommodate a change in both.
If a centrifugal pump is started with the discharge valve open too far and with a low discharge pressure, the liquid in the suction line may accelerate at a rate that causes the suction pressure to drop below vapor pressure.
Last month, we looked at adjustable frequency AC drive system, induction motor speed control and motor application and performance. This month we will explore specific operation conditions, applications and performance.