Overload protection
Each supply voltage output has overload protection for the output voltages US and UP. If an output voltage is switched off due to overload, all other output voltages remain switched on.
The overload protection comprises two protection mechanisms:
- Overload switch-off, configurable
- Current limitation, not configurable
| EP92x4-0023 HW 16 and higher | EP92x4-0023 HW 15 and lower | EP92x4-0024 |
|---|---|---|---|
Nominal current (default) | 4.0 A | 4.0 A | 4.0 A |
Current limitation | 4.4 A | 7.0 A | 4.4 A |
Thermal switch-off time | typ. 160 ms | typ. 50 ms | typ. 160 ms |
Above the set nominal current, the status bit "Warning" is set. In this range, the protection mechanisms are active as follows:
- If the output current is between the nominal current and the current limit, only the overload switch-off is active. It switches off the respective output voltage according to the configured tripping characteristic.
See chapter Configure overload switch-off. - When the output current reaches the current limit, overload switch-off and current limitation are active simultaneously.
The output voltage is either switched off by the overload switch-off according to the switch-off characteristic or, in the event of thermal overload, by the starting current limitation; depending on which mechanism triggers first. The switch-off time of the current limitation depends on the ambient conditions.
You can use the data logger to determine which of the two protection mechanisms has switched off an output voltage. See chapter Troubleshooting with the data logger.
Overload message
If the overload protection has switched off an output voltage, this is reported as follows:
- The status bit “Error Us” or “Error Up” of the channel is set.
- The output voltage status LED of the channel lights up red.
Resetting an error state
If an output voltage has been switched off by the overload protection, it can be enabled again by one of the following actions:
- a positive edge at the output variable “DPO Inputs Channel n” > “Reset Ux” of the respective channel
- a positive edge on the output variable "DPO Outputs Device" > "Global Reset"
- Reset contact, see chapter Monitoring and reset contacts.
A reset is possible every 20 s at most. Faster successive edges are ignored.
This also resets the status bit “Error Us” or “Error Up”.