Power entry and energy storage

VFD input rectifier, precharge and DC-link path

Routes incoming three-phase supply through protection, rectification, precharge and DC-link storage before the inverter stage is allowed to run.

Functional path

Input terminals

Line fuses / contactor

Rectifier bridge

Precharge resistor or relay/contactor

DC-link capacitors

DC bus feedback

Diagnostic signals and checkpoints

No display with line presentUndervoltagePrecharge faultBlown input fuseDC bus not reaching expected level

Technician notes

Precharge faults can mimic a control-board problem.
Capacitor condition affects ripple, startup and braking behavior.
DC-link feedback errors can create false undervoltage or overvoltage decisions.