Reliance 2364p-um000_-en-p DC bus power front end

Reliance 2364p-um000_-en-p DC bus power front end

Description

The parallel configuration, a DC bus supply front-end with  regenerative capability, is used to supply DC power for AC digital  drive inverter units in a common bus drive system. Twenty-three  different parallel configurations provide a spectrum of different  supply and regenerative capabilities.

Parallel configurations use the following front-end units: 

• Regenerative DC Bus Supply Unit (RGU) 

• Non-Regenerative DC Bus Supply Unit (NRU) 

Each parallel configuration will include one, two, or three  Regenerative DC Bus Supply Units (RGUs). These units are used to  supply motoring current to the DC bus, and are used to regenerate  current back onto the AC line. 

Most of the parallel configurations will also include a  Non-Regenerative DC Bus Supply Unit (NRU) to supply the  motoring current to the DC bus.

RGU//RGU Configurations 

In an RGU//RGU configuration, each RGU supplies 100% motoring  current and 100% regenerative current. When operating, the master  RGU evaluates the bus voltage and sends current commands to the  slave RGUs through an RGU-to-RGU (R2R) communication  network. This allows the RGUs to operate together to supply the  appropriate current while maintaining a constant voltage on the DC  bus.

Precharge Operation 

When the disconnects are closed and the start switch is turned  on, each RGU in the parallel configuration will begin its  precharge routine. This routine charges the capacitors on the  DC bus (the RGU capacitor bank and inverter capacitors) in a  controlled fashion. 

Two contactors (M1 and M2) are used to perform the precharge  operation in the K, L, and M-code RGUs (the N-code RGU precharge  circuit is slightly different). 

When the disconnect (MCP1 or CB1) is closed and the start switch is  turned on, the main contactor (M1) remains open, the precharge  contactor (M2) closes, and current begins to flow through the  precharge circuit (bypassing the main 3-phase circuit). This  precharge circuit (which has a resistive load) charges up the capacitor  bank. As the bank approaches capacity, the main contactor (M1)  closes, the precharge contactor (M2) opens, the NRU circuit breaker  closes, and normal operation begins.