Practice Tasks

Hands-on exercises for VFD commissioning, PLC programming, and fault diagnostics.

Training reference only. Always follow OEM manual, lockout/tagout procedures, and site safety rules before attempting any task on real equipment.
All VFD PLC Fault | All Levels Beginner Intermediate
Parameter Library Fault Lab Courses
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VFD Intermediate Delta, Siemens, ABB

Configure VFD Modbus Communication

VFD aur PLC ke beech RS-485 wiring karke, Modbus address aur baud rate set karke, run/stop aur speed command bhejana.

Wire RS-485 between VFD and PLC/laptop, set Modbus address and baud rate, send run/stop and speed commands via Modbus.

Steps
  1. Wire RS-485: A+ to A+, B- to B-, GND to GND between VFD and master
  2. Set VFD Modbus address (e.g. 1)
  3. Set baud rate to match master (e.g. 9600, 8-N-1)
  4. Set VFD start/stop source = Communication
  5. Set speed reference source = Communication
  6. From PLC/laptop Modbus tool: send Run command, then speed reference
  7. Verify motor starts and runs at commanded speed
  8. Send Stop command, verify motor stops
Common Mistake: Swapped A/B wires (some brands reverse polarity). Missing bus termination resistor on long cables. Wrong data format (parity/stop bits).
⚠ Set communication loss action parameter to 'Stop' or 'Coast' — never 'Continue running' during commissioning.
Related courses: vfd-starter
PLC Intermediate Siemens, Mitsubishi

Program Star-Delta Starter in PLC

PLC mein Star-Delta starter ka ladder logic likhna — timer, interlock, aur safety checks ke saath.

Write ladder logic for Star-Delta motor starting with timer transition, contactor interlocks, and safety checks.

Steps
  1. Define I/O: X0=Start, X1=Stop, X2=E-Stop, Y0=Main contactor, Y1=Star contactor, Y2=Delta contactor
  2. Sequence: Start → Y0+Y1 (Main+Star) → Timer 5s → Y1 OFF, 50ms delay, Y2 ON (Delta)
  3. Interlock: Y1 and Y2 must NEVER be ON simultaneously
  4. Add interlocks in ladder: Y1 NC contact in Y2 rung, Y2 NC contact in Y1 rung
  5. Add timer (TON, 5 seconds) triggered by Y1 output
  6. Stop/E-Stop → all outputs OFF immediately
  7. Test: observe current drop when switching from Star to Delta
Common Mistake: No interlock between Star and Delta contactors — simultaneous ON = phase-to-phase short circuit. Timer too short — motor hasn't reached speed.
⚠ Star-Delta transition has a brief open period — motor coast causes transient. Ensure interlock is both in PLC and hardwired.
Related courses: plc-starter

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