ABB ACS880-304LC Series, Руководство по оборудованию, Страница: 15 / 178

Operation principle and hardware
description
Contents of this chapter
This chapter describes how the diode supply unit works and the hardware of the diode
supply module.
Operation principle
The heart of the diode supply unit is a diode bridge. It rectifies three-phase AC current
to direct current for the intermediate DC link of the drive. The intermediate DC link
supplies the inverters that run the motors. There can be one inverter unit only (single
drives) or several inverter units (multidrives) connected to the intermediate circuit.
The rectifier bridge in the supply module is uncontrolled: it cannot control the DC link
voltage or limit the charging current of the DC link capacitors at the power up. Thus
you can only use the bridge with inverters that have charging circuits, or you must
equip the supply unit with a separate charging circuit.
Note:
• The supply module does not have means to control, limit or cut off the load current.
• The customer must arrange the overload and short-circuit protection of each
supply cable (typically with fuses).
• The supply unit does not have AC or DC chokes. Thus, the customer must arrange
a sufficient inductance at the AC side of each supply module with suitable cabling.
The minimum length of the supply cable per each supply module is 5 meters (16.4
feet). The inductances between the parallel-connected supply modules must be
identical, ie, the cabling to each module must be identical in regard to cable type
and length. For selecting the supply transformer, see
Selecting the supply
transformer .
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