OLr / H (Resistor OL) Dynamic Braking Resistor Overload fault in Toshiba drive
OLr / H (Resistor OL) Dynamic Braking Resistor Overload fault in Toshiba drive
Description This fault relates to the Dynamic Braking Resistor (DBR) circuit. When a load is stopped quickly, the motor generates energy. The drive dissipates this energy as heat into an external resistor. The OLr fault acts as a thermal protection for that resistor. The drive calculates the duty cycle of the braking; if the resistor is used too frequently, it calculates that the resistor is about to melt or catch fire and trips to stop the process. Causes
1. Duty Cycle Exceeded: The machine is stopping and starting too frequently (e.g., a lift or press), not giving the resistor time to cool.
2. Undersized Resistor: The wattage rating of the installed resistor is too low for the application's inertia.
3. Parameter Settings: The "Braking Resistor Capacity" (kW) and "Resistance Value" (Ohms) parameters in the drive do not match the physically installed resistor.
4. Chopper Transistor Failure: If the internal braking transistor shorts, it pumps current to the resistor continuously until it overheats. Solution Check the parameters first. Ensure the entered Braking Resistor kW (P.Cap) and Ohms match the label on the resistor bank. If these are correct, touch the resistor (CAUTION: It may be extremely hot). If it is glowing red or scorching paint, the application is too aggressive.
You have two choices: 1. Increase the Deceleration Time (DEC). This reduces the amount of regeneration energy sent to the resistor. 2. Upgrade the resistor hardware. Install a resistor with a higher Wattage/kW rating (keeping the Ohms the same) and update the drive parameter.
If the resistor is cold but the drive trips OLr immediately upon power up, the drive's internal calculation is corrupted or the detection circuit is faulty. If the resistor gets hot instantly when the drive is idle (motor stopped), the internal IGBT braking chopper is shorted, and the VFD unit must be replaced.
Description This fault relates to the Dynamic Braking Resistor (DBR) circuit. When a load is stopped quickly, the motor generates energy. The drive dissipates this energy as heat into an external resistor. The OLr fault acts as a thermal protection for that resistor. The drive calculates the duty cycle of the braking; if the resistor is used too frequently, it calculates that the resistor is about to melt or catch fire and trips to stop the process. Causes
1. Duty Cycle Exceeded: The machine is stopping and starting too frequently (e.g., a lift or press), not giving the resistor time to cool.
2. Undersized Resistor: The wattage rating of the installed resistor is too low for the application's inertia.
3. Parameter Settings: The "Braking Resistor Capacity" (kW) and "Resistance Value" (Ohms) parameters in the drive do not match the physically installed resistor.
4. Chopper Transistor Failure: If the internal braking transistor shorts, it pumps current to the resistor continuously until it overheats. Solution Check the parameters first. Ensure the entered Braking Resistor kW (P.Cap) and Ohms match the label on the resistor bank. If these are correct, touch the resistor (CAUTION: It may be extremely hot). If it is glowing red or scorching paint, the application is too aggressive.
You have two choices: 1. Increase the Deceleration Time (DEC). This reduces the amount of regeneration energy sent to the resistor. 2. Upgrade the resistor hardware. Install a resistor with a higher Wattage/kW rating (keeping the Ohms the same) and update the drive parameter.
If the resistor is cold but the drive trips OLr immediately upon power up, the drive's internal calculation is corrupted or the detection circuit is faulty. If the resistor gets hot instantly when the drive is idle (motor stopped), the internal IGBT braking chopper is shorted, and the VFD unit must be replaced.
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