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Drives Service & Support > 160 > db
160 Series C Dynamic Brake Operation
The Bulletin 160 series C dB operation is controlled through Parameter 52 [DB Enable]. With a setting of 0, the external dB is disabled and internal software will change the deceleration rate to limit the bus voltage rise. If this voltage rise cannot be limited, the drive will trip with a fault 5 [Overvoltage fault].
Any value other than 0 will indicate the duty cycle the drive will apply to an external dB resistor. The drive will let the external resistor rise to its maximum temperature by apply 100% duty cycle. When it has reached its maximum temperature the duty cycle drops down to the duty cycle programmed in parameter 52. The maximum time that 100% duty cycle is applied is for 80 seconds. This maximum time is achieved with parameter 52 settings of 5 or greater. Below 5 the 100% duty cycle lasts for 16 (seconds) times the setting in parameter 52. For example: if parameter 52 were set to 3, then the drive would apply 100% duty cycle to the external dB resistor for 48 seconds (3 * 16), and then drop down to 3%.
The drive will also model the cooling of the external dB resistor. This is done through a dB running counter. This counter counts down while the dB is running at 100%. When it reaches zero the drive switches to the duty cycle programmed in parameter 52. When the dB is not running the counter counts up at a different rate. The rate of recovery for various parameter 52 settings is shown in the table below. Note that the counter counts up whenever the dB is not running. This can be when the drive is in standby, while it is running at speed, while it is accelerating, or even decelerating with the dB not active.
| Parameter 52 Setting | Time to recover after one second on (seconds) |
| 5 | 20.00 |
| 10 | 9.00 |
| 20 | 4.00 |
| 30 | 2.40 |
| 40 | 1.50 |
| 50 | 1.00 |
| 60 | 0.67 |
| 70 | 0.43 |
| 80 | 0.25 |
All counters are cleared when the power is cycled. If the power is turned off and then on again, the drive sees the resistor as "cold." If this is done to "gain" additional 100% duty cycle time, the dB resistor will fail. When the power is turned off the dB resistor should be allowed to cool before the drive is required to perform heavy braking.
