EL9570 by Beckhoff

The EL9570 is an energy-buffering terminal from Beckhoff that belongs to the EL EtherCAT Terminals series. Installed alongside standard I/O nodes, this unit provides capacitive ballast so distributed control panels can ride through short-duration voltage dips and switching transients. By stabilizing the local 50 V DC link, it helps protect sensitive EtherCAT electronics and actuators from voltage fluctuations that occur when loads change abruptly in automated machinery. The terminal can be integrated into an EtherCAT I/O assembly without requiring a separate buffering module elsewhere in the control cabinet.

The terminal has a nominal operating voltage of 50 V, which serves as the reference point for its other electrical data. The housing contains a storage bank rated at 500 µF, allowing it to absorb or supply charge during disturbances lasting only milliseconds. Its continuous ripple-current capacity reaches 10 A, accommodating current drawn by clustered converters and contactor coils without overheating the electrolytic elements. Low conduction losses are supported by an internal resistance of < 10 m?, so most of the bus energy reaches the load rather than being dissipated as heat. A series ballast resistor rated at 10 ? works with the two-point ballast control circuit to limit inrush current and reconnect the capacitor after the voltage returns to its normal operating range.

Overvoltage behavior is governed by a threshold window of ±2 V, allowing the device to disconnect when the DC rail moves outside the permitted range. During a supply spike, surge suppression activates at voltages above 56 V, helping prevent insulation stress on downstream terminals. The plastic enclosure has an IP20 protection rating, making it finger-safe when mounted inside a cabinet while leaving it unsealed against water. Standard DIN-rail installation is supported by a 35 mm rail foot, and the mounting position can be varied to accommodate crowded backplanes. The terminal does not have a protective earth contact, so protective earth continuity must be provided by the supporting I/O rack.