Brake check

What does 28 mean?

The brake resistor is either not connected to the drive, or it is not functioning correctly (e.g., open circuit). This means the drive cannot dissipate regenerative energy, potentially leading to DC overvoltage faults during deceleration if braking is required.

• Open circuit in the external brake resistor wiring, such as a broken cable or loose connection at drive terminals B1/B2 or resistor terminals.
• The external brake resistor itself has failed (e.g., internal element broken due to overheating or mechanical shock).
• Incorrect brake resistor value (resistance or power rating) connected, causing the drive to misinterpret its presence.
• Faulty internal current sensing circuit within the drive responsible for monitoring the brake resistor connection.

Click steps to track your progress.

1. 1

   De-energize the drive and wait for DC bus discharge (verify 0VDC at DC+ / DC- terminals).

2. 2

   Measure the resistance of the external brake resistor directly at its terminals, verifying it matches the specified value (e.g., 20 Ohms).

3. 3

   Measure continuity of the brake resistor cables from the drive's B1 and B2 terminals to the resistor terminals.

4. 4

   Confirm Parameter P5-10 (Brake Resistor Ohms) is set correctly to the actual resistance of the connected brake resistor.

5. 5

   Inspect drive terminals B1 and B2 for secure connections and absence of corrosion.