Industrial Engineer · phase 10 of 16
DC Bus Voltage
Voltage on the DC link, typically near 1.35 to 1.41 times the AC line-to-line RMS voltage depending on rectifier topology, loading, and ripple.
The Explain card
- Plain English
- The bus voltage is the DC level between the rectifier and the inverter. On a plain diode front end it sits a little below the peak of the incoming line, which is about one and four tenths times the RMS line to line voltage.
- Example
- A 480 volt supply gives a bus near 650 volts DC at light load. During a hard deceleration the same bus climbs toward 800, and an overvoltage trip lands around there.
- Why it matters
- Nearly every voltage fault on a drive is a bus fault. High means regeneration or a high line, low means a sag, a lost phase or a tired capacitor, and the keypad's bus reading is the first diagnostic.
- Hook
- The one voltage inside the drive that tells the story.
Where it sits in the deck
Phase 10: VFD Electrical and Motor Fundamentals
The physics under the parameters: slip, torque, flux, and the relationship between frequency and voltage that every drive is really controlling.
