EL2798 BECKHOFF EtherCAT Terminal 8-Channel Solid State Relay Output

Product Overview

The EL2798 (EL2798) is a high-density EtherCAT Terminal featuring eight potential-free solid-state relay (SSR) outputs, designed to bridge the gap between traditional mechanical relays and high-speed digital switching. Engineered for precision control in automated systems—such as HVAC management, light chemical processing, and general industrial sequencing—the EL2798 functions as a highly reliable electronic substitute for conventional make contacts. By utilizing semiconductor technology instead of moving parts, this module eliminates contact wear and mechanical arcing, significantly extending the service life of the control interface. With a substantial 2 A current capacity per channel and an ultra-low on-resistance of 0.03 Ohms, it ensures efficient power transmission with minimal thermal loss in high-duty cycle applications.

Technical Configuration

The EL2798 is housed in a compact 12 mm High Density (HD) enclosure, utilizing 2-wire connection technology to manage eight independent make contacts. The hardware architecture supports a versatile voltage range up to 30 VAC or 48 VDC (ohmic), providing complete electrical isolation of 500 V between the internal E-bus and the field potential. Unlike standard digital outputs, these potential-free contacts allow for the switching of different voltage levels across various channels, provided the channel-to-channel isolation remains under 200 V. The module is optimized for durability, featuring a peak current tolerance of 50 A for 10 ms to handle initial inrush currents, while maintaining a low current consumption from the E-bus of typically 140 mA.

Technical Specifications

Technical FAQs

Can the EL2798 switch inductive loads like large solenoid valves?

The EL2798 is optimized for ohmic loads. If used with inductive loads, external protective circuitry (such as recovery diodes for DC or varistors for AC) must be installed to suppress back-EMF. The module is not short-circuit proof, so ensuring that peak currents remain within the 5 A (100 ms) limit is critical for hardware longevity.

What are the primary advantages of this solid-state relay over a standard EL2602 mechanical relay?

The primary advantages are zero mechanical wear and silent switching. While mechanical relays have a finite number of switching cycles, the solid-state design of the EL2798 can handle virtually unlimited operations at a faster "on" speed (1.8 ms). It is the ideal choice for applications involving high-frequency switching or where explosive arcing must be avoided.

Are the outputs truly independent for different power sources?

Yes, the outputs are potential-free, meaning they are not tied to a common internal power rail. You can switch different external circuits through each channel. However, maintain a maximum potential difference of less than 200 V between any two adjacent channels to ensure the integrity of the internal isolation.

Engineering & Installation Guide

• Thermal Management: When operating multiple channels at the maximum 2 A rating, the total module current (sum) must not exceed 10 A. Ensure sufficient ventilation in the control cabinet. In high-density DIN rail configurations, it is recommended to maintain a 0 to +55 Celsius ambient environment to prevent thermal derating of the solid-state components.

• Wiring and Termination: Utilize the HD housing's spring-actuated terminals for gas-tight connections. For flexible conductors with ferrules, the recommended cross-section is 0.14 to 0.75 mm squared. Ensure a stripping length of 8 to 9 mm to prevent exposed wire or poor contact, which could increase resistance and heat generation at the terminal.

• Short-Circuit Protection: Since the EL2798 is not short-circuit proof, it is mandatory to install ultra-fast-acting fuses or appropriate circuit breakers upstream of the field-side supply. This protects the internal semiconductor switches from catastrophic failure in the event of a field wiring fault or load short.