EM-A41 is a power-input front-end card for DC motor controllers and other compatible electronic loads. It is designed for applications requiring low standby current, controlled power switching and a hardware-based emergency shutdown input.
A built-in pre-charge circuit limits the charging current of capacitive loads before the main relay closes. This reduces the current surge at power-up and helps protect the main relay contacts from excessive inrush current.
Many motor controllers and other electronic devices have large input capacitors. Connecting an uncharged capacitor bank directly to a power source can cause a very high momentary current that damages or shortens the service life of mechanical relay contacts.
The EM-A41 initially charges the connected capacitance through a controlled pre-charge path. The main relay is switched on after the pre-charge phase, reducing the current surge through the relay contacts and the upstream power switch.
The card is activated by a voltage applied to either the FW or BW wake-up line. An active level of 4–35 V wakes the system and enables the main power path.
When neither wake-up command remains active, the EM-A41 returns to sleep mode after approximately 30 seconds. The specified sleep-mode current is 0.7 mA.
The emergency-shutdown function is implemented using a hardware circuit and has the highest internal control priority. The specified emergency-switch arrangement uses a normally closed contact.
Opening the emergency circuit causes the EM-A41 to disconnect the controlled power path. The complete machine-level emergency-stop function must nevertheless be designed and validated according to the safety requirements of the final application.
The EM-A41 monitors the operation of its main relay. If the relay does not follow the commanded state, for example because its contacts remain stuck, the monitoring circuit can indicate a fault through the NPN fault output.
The card supports a maximum continuous load current of 30 A at ambient temperatures below 50 °C and a maximum peak current of 40 A for 10 seconds. The specified voltage drop is approximately 0.2 V at 30 A.
| Function | Power-input front end with pre-charge, sleep and emergency-shutdown functions |
|---|---|
| Supply voltage | 10–35 VDC |
| Maximum continuous current | 30 A at Ta < 50 °C |
| Maximum peak current | 40 A for 10 s |
| Voltage drop | 0.2 V at 30 A |
| Calculated power loss at 30 A | Approximately 6 W |
| Sleep-mode current | 0.7 mA |
| Switch-on time | 50 ms |
| Switch-off time | 5 ms |
| Automatic sleep delay | 30 s after the last active command |
| Wake-up inputs | FW and BW |
| Wake-up voltage | 4–35 V |
| Wake-up input impedance | 47 kΩ |
| Recommended emergency switch | Normally closed contact, minimum rating 1 A |
| Fault output | NPN, maximum 30 V / 50 mA |
| Supply connectors | Maximum conductor size 6 mm² |
| Control connectors | Maximum conductor size 1.5 mm² |
| Operating temperature (Ta) | −40 … +60 °C |
| EMC | EN 50081-2 and EN 50082-2, industrial environment |
| Weight | 55 g |
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