231-8310

Check motor brake connector

Inspect the brake connector at the servo motor for loose pins, corrosion, or damage. Verify proper seating of the brake cable connector.

Ensure machine power is OFF and LOTO procedures are followed before handling electrical connections.

Measure brake coil resistance

Using a multimeter, measure resistance across the brake coil terminals. Typical values are 50-200 ohms depending on motor size. Open circuit indicates coil failure.

Check the motor nameplate or Heidenhain documentation for specific brake coil resistance values for your motor model.

Inspect brake cable routing

Trace the brake cable from motor to inverter checking for pinched, cut, or damaged sections especially at cable carriers and bend points.

Flex the cable while measuring continuity to detect intermittent breaks in stranded conductors.

Check inverter brake output voltage

Measure DC voltage at inverter brake output terminals during brake test. Should read 24VDC or motor-specific brake voltage when brake is commanded to release.

Use proper PPE and insulated test equipment when measuring live circuits.

Verify inverter status LEDs

Check inverter front panel LEDs for fault indications. Red fault LED or specific brake fault indicators suggest internal inverter problems.

Consult the inverter manual for LED fault code interpretation specific to your Heidenhain inverter model.

Review inverter parameters

Access TNC parameter menu and verify brake-related parameters are correctly configured for your motor type and brake specifications.

Parameter 1420 typically controls brake delay timing - incorrect values can cause brake test failures.

Perform brake coil insulation test

Using a megohmmeter, test insulation resistance between brake coil and motor frame. Should read >1 megohm. Low readings indicate coil insulation breakdown.

Disconnect all wiring before performing insulation tests to prevent damage to control circuits.

Check for mechanical brake seizure

With power off and brake engaged, attempt to manually rotate the motor shaft. Excessive resistance may indicate seized brake mechanism.

Some resistance is normal with brake engaged, but shaft should not be completely locked if brake is functioning properly.

Monitor brake current during test

Use clamp-on ammeter to measure actual current flow to brake coil during TNC brake test sequence. Compare to motor specifications.

Typical brake coils draw 0.5-2.0 amps depending on motor size. No current flow confirms coil failure.

Verify axis configuration parameters

Access Machine Parameters menu and check axis-specific brake parameters match the installed motor specifications and inverter capabilities.

Parameters 1410-1430 series typically control brake functions - ensure these match your motor documentation.

Check brake test timing settings

Review brake test sequence timing parameters to ensure adequate time is allowed for brake coil energization and current stabilization.

Increase brake test delay if marginal current readings are detected during the test sequence.

Perform manual brake test

Use TNC manual brake control function to manually energize/de-energize brake while monitoring current flow to isolate automatic test issues.

Manual brake control is typically found in the axis diagnostic menu under brake functions.