Regen Overview - Danfoss VLT AutomationDrive FC 302 Design Manual

Product Features
Load sharing
Units with the built-in load sharing option contain terminals (+) 89 DC and (–) 88 DC. Within the drive, these terminals
connect to the DC bus in front of the DC-link reactor and bus capacitors.
The load sharing terminals can connect in 2 different configurations.
•
Terminals tie the DC-bus circuits of multiple drives together. This configuration allows a unit that is in a
regenerative mode to share its excess bus voltage with another unit that is running a motor. Load sharing in this
manner can reduce the need for external dynamic brake resistors, while also saving energy. The number of units
that can be connected in this way is infinite, as long as each unit has the same voltage rating. In addition,
depending on the size and number of units, it may be necessary to install DC reactors and DC fuses in the DC-link
connections, and AC reactors on the mains. Attempting such a configuration requires specific considerations.
•
The drive is powered exclusively from a DC source. This configuration requires:
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5.6 Regen Overview

Regen typically occurs in applications with continuous braking such as cranes/hoists, downhill conveyors, and centrifuges
where energy is pulled out of a decelerated motor.
The excess energy is removed from the drive using 1 of the following options:
•
Brake chopper allows the excess energy to be dissipated in the form of heat within the brake resistor coils.
•
Regen terminals allow a third-party regen unit to be connected to the drive, allowing the excess energy to be
returned to the power grid.
Returning excess energy back to the power grid is the most efficient use of regenerated energy in applications using
continuous braking.
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VLT® AutomationDrive FC 302
A DC source.
A means to soft charge the DC bus at power-up.
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