Mitsubishi Elevator Brake Circuit (BK) Troubleshooting Guide

Brake Circuit (BK)

1 Overview

Brake circuits Are categorized into two types: current-controlled and resistive voltage divider-controlled. Both consist of drive circuits and contact feedback circuits.

1.1 Current-Controlled Brake Circuit

• Structure:

  • Drive Circuit: Powered by #79 or S420, controlled via #LB contactor.

  • Feedback Circuit: Brake contact signals (open/closed) sent directly to W1/R1 boards.

• Operation:

  1. #LB contactor closes → Control unit (W1/E1) activates.

  2. Control unit outputs brake voltage → Brake opens.

  3. Feedback contacts transmit armature status.

Schematic:

1.2 Resistive Voltage Divider-Controlled Brake Circuit

• Structure:

  • Drive Circuit: Includes voltage-dividing resistors and feedback contacts.

  • Feedback Circuit: Monitors armature position via NC/NO contacts.

• Operation:

  1. Brake Closed: NC contacts short-circuit resistors → Full voltage applied.

  2. Brake Open: Armature moves → NC contacts open → Resistors reduce voltage to maintenance level.

  3. Enhanced Feedback: Additional NO contacts verify brake closure.

Key Note:

• For ZPML-A traction machines, brake gap adjustment directly affects armature travel (optimal: ~2mm).

2 General Troubleshooting Steps

2.1 Brake Action Failures

Symptoms:

• Brake fails to open/close (single or both sides).

• Note: Complete brake failure may cause car slippage (critical safety hazard).

Diagnostic Steps:

1. Check Voltage:

   • Verify full voltage pulse during opening and maintenance voltage afterward.

   • Use multimeter to measure coil voltage (e.g., 110V for #79).

2. Inspect Contacts:

   • Adjust contact alignment (center for current control; near travel end for resistive control).

3. Mechanical Checks:

   • Lubricate linkages; ensure no obstructions in armature path.

   • Adjust brake gap (0.2–0.5mm) and torque spring tension.

2.2 Feedback Signal Faults

Symptoms:

• Brake operates normally, but P1 board shows brake-related codes (e.g., "E30").

Diagnostic Steps:

1. Replace Feedback Contacts: Test with known-good components.

2. Adjust Contact Position:

   • For resistive control: Align contacts near armature travel end.

3. Check Signal Wiring:

   • Verify continuity from contacts to W1/R1 boards.

2.3 Combined Faults

Symptoms:

• Brake action failure + fault codes.

Solution:

• Perform full brake adjustment using tools like ZPML-A Brake Calibration Device.

3 Common Faults & Solutions

3.1 Brake Fails to Open

3.2 Insufficient Braking Torque

4. Diagrams

Figure : Brake Circuit Schematics

• Current Control: Simplified topology with independent drive/feedback paths.

• Resistive Control: Voltage-dividing resistors and enhanced feedback contacts.

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

© Elevator Maintenance Technical Documentation