Elevator Main Electrical Circuit Troubleshooting Guide - Main Circuit (MC)

1 Overview

The MC circuit consists of three pArts: input section, main circuit section, and output section.

Input Section

• Starts from the power input terminals.

• Passes through EMC components (filters, reactors).

• Connects to the Inverter module via control contactor #5 (or rectifier module in energy regeneration systems).

Main Circuit Section

• Core components include:

  • Rectifier: Converts AC to DC.

    • Uncontrolled Rectifier: Uses diode bridges (no phase sequence requirement).

    • Controlled Rectifier: Uses IGBT/IPM modules with phase-sensitive control.

  • DC Link:

    • Electrolytic capacitors (series-connected for 380V systems).

    • Voltage-balancing resistors.

    • Optional regeneration resistor (for non-regenerative systems to dissipate excess energy).

  • Inverter: Converts DC back to variable-frequency AC for the motor.

    • Output phases (U, V, W) pass through DC-CTs for current feedback.

Output Section

• Starts from the inverter output.

• Passes through DC-CTs and optional EMC components (reactors).

• Connects to the motor terminals.

Key Notes:

• Polarity: Ensure correct "P" (positive) and "N" (negative) connections for capacitors.

• SNUBBER Circuits: Installed on IGBT/IPM modules to suppress voltage spikes during switching.

• Control Signals: PWM signals transmitted via twisted-pair cables to minimize interference.

Figure 1-1: Uncontrolled Rectifier Main Circuit

2 General Troubleshooting Steps

2.1 Principles for MC Circuit Fault Diagnosis

1. Symmetry Check:

   • Verify all three phases have identical electrical parameters (resistance, inductance, capacitance).

   • Any imbalance indicates a fault (e.g., damaged diode in rectifier).

2. Phase Sequence Compliance:

   • Follow wiring diagrams strictly.

   • Ensure control system phase detection aligns with the main circuit.

2.2 Opening Closed-Loop Control

To isolate faults in closed-loop systems:

1. Disconnect Traction Motor:

   • If the system operates normally without the motor, the fault lies in the motor or cables.

   • If not, focus on the control cabinet (inverter/rectifier).

2. Monitor Contactor Actions:

   • For regenerative systems:

     • If #5 (input contactor) trips before #LB (brake contactor) engages, check the rectifier.

     • If #LB engages but issues persist, check the inverter.

2.3 Fault Code Analysis

• P1 Board Codes:

  • E.g., E02 (overcurrent), E5 (DC link overvoltage).

  • Clear historical faults after each test for accurate diagnosis.

• Regenerative System Codes:

  • Check phase alignment between grid voltage and input current.

2.4 (M)ELD Mode Faults

• Symptoms: Sudden stops during battery-powered operation.

• Root Causes:

  • Incorrect load weighing data.

  • Speed deviation disrupting voltage balance.

• Check:

  • Verify contactor actions and output voltage.

  • Monitor P1 board codes before (M)ELD shutdown.

2.5 Traction Motor Fault Diagnosis

3 Common Faults & Solutions

3.1 PWFH(PP) Indicator Off or Flashing

• Causes:

  1. Phase loss or incorrect sequence.

  2. Faulty control board (M1, E1, or P1).

• Solutions:

  • Measure input voltage and correct phase order.

  • Replace the defective board.

3.2 Magnetic Pole Learning Failure

• Causes:

  1. encoder misalignment (use dial indicator to check concentricity).

  2. Damaged encoder cables.

  3. Faulty encoder or P1 board.

  4. Incorrect parameter settings (e.g., traction motor configuration).

• Solutions:

  • Reinstall encoder, replace cables/boards, or adjust parameters.

3.3 Frequent E02 (Overcurrent) Fault

• Causes:

  1. Poor module cooling (clogged fans, uneven thermal paste).

  2. Brake misadjustment (gap: 0.2–0.5mm).

  3. Defective E1 board or IGBT module.

  4. Motor winding short-circuit.

  5. Faulty current transformer.

• Solutions:

  • Clean fans, reapply thermal paste, adjust brakes, or replace components.

3.4 General Overcurrent Faults

• Causes:

  1. Driver software mismatch.

  2. Asymmetric brake release.

  3. Motor insulation failure.

• Solutions:

  • Update software, synchronize brakes, or replace motor windings.

Document Notes:
This guide aligns with Mitsubishi elevator technical standards. Always follow safety protocols and refer to official manuals for model-specific details.

© Elevator Maintenance Technical Documentation