Low Voltage Dc Operation - Emerson Unidrive M700 User Manual

For operation with a UPS the external contactors are managed by the Elevator controller to connect
and disconnect both the AC supply and UPS supply, both of these being synchronized. The AC
supply and UPS supply inrush current is managed through the drives half controlled rectifier.
.
2.3.3 Contactor control
The contactor control for the transition from the AC supply to Low voltage DC supply can be managed
locally by the drive when operating in Low voltage DC mode using the on-board control to manage
seem-less control Pr 06.068 - Low Voltage DC Mode Enable = On (1).
Alternatively when operating in Low voltage DC mode the transition from the AC supply to the Low
voltage DC supply can be managed externally by the Elevator controller. In the instance the Elevator
controller is managing the transition using Pr 06.067 - Low Under Voltage Threshold = On (1). The
transition from the AC supply to Low voltage DC supply must consider, and manage the inrush
current when connecting power supplies, for drive frame sizes 7 and larger using an external soft start
circuit. Pr 06.067 - Low Under Voltage Threshold can also be managed by the Elevator controller
selecting based upon the active power supply.
NOTE:
It is important to consider pre charging of the drive when applying either the AC or the Low voltage
DC power supply, and during transitioning between power supplies.
2.4

Low voltage DC operation

Low voltage DC operation is available on all drives, and can typically be used to support the following
modes of operation in Elevator systems.
2.4.1 Low voltage DC mode for Rescue operation
Low voltage DC mode is used to provide rescue operation for the Elevator system where the AC
supply is no longer available. This operation requires the Low voltage DC supply or UPS to deliver
power to the drive, Elevator controller and motor along with motor contactors, brakes, auxiliary
components, which could include door controller and car lighting etc. The Low voltage DC supply for
rescue operation is rated to supply the complete Elevator system, and deliver the required operating
power to the motor. The Low voltage DC supply could come from either
a) DC battery supply system connected directly to the drives DC Bus
b) UPS system connected via the drives AC rectifier input stage
Low voltage DC supply
•
Pre charging of the drive when first applying the AC supply for drive frame sizes 3 to 6 will be
using the drives internal soft start circuit.
- Transitioning from the AC supply to the Low voltage DC supply where the DC Bus is already
charged does not require any soft start to be active
- During a transitioning from the Low voltage DC supply to the AC supply the drive must be in
the Under Voltage state where the soft start circuit is active to limit the AC inrush current.
- Connecting the Low voltage DC supply where the DC Bus is discharged will use the drives
internal soft start circuit.
•
Pre charging of the drive when first applying the AC supply for drive frame sizes 7 and larger will
be using the drives half controlled rectifier.
- Transitioning from the AC supply to the Low voltage DC supply where the DC Bus is already
charged does not require any pre-charging
- During a transitioning from the Low voltage DC supply to the AC supply the drives half
controlled rectifier will limit the AC inrush current.
- Pre charging for the Low voltage DC supply where the DC Bus is discharged requires an
external soft start circuit.
UPS supply
•
Pre charging of the drive when first applying the AC supply for drive frame sizes 3 to 6 will be
using the drives internal soft start circuit.
- Transitioning from the AC supply to the UPS supply where the DC Bus is already charged
does not require any soft start to be active
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