Beckhoff KL2634 Bus Terminal

Product Overview

The Beckhoff KL2634 is a 4-channel digital output terminal from the K-bus series, featuring four independent relay outputs with make contacts (normally open). Designed for versatile switching, this terminal is ideal for applications requiring galvanic isolation between the control system and the load, such as switching contactors, small motors, or solenoids. Because it utilizes mechanical relay contacts, it is well-suited for both AC and DC loads, offering a robust, industrial-grade solution for power-switching tasks within a Beckhoff Bus Terminal system.

Technical Configuration

The KL2634 provides direct, high-current switching capabilities integrated into the modular Bus Terminal architecture.

• Relay Switching: Each of the four channels operates as a make contact, allowing for the switching of voltages up to 250 V AC or 30 V DC.
• Galvanic Isolation: The terminal provides 500 V electrical isolation between the K-bus (logic) and the field potential (load), ensuring that electrical noise or surges on the power side do not damage the PLC logic.
• Compact Design: Like all K-bus terminals, it occupies a minimal footprint on the DIN rail, simplifying the cabinet layout.
• Status Indication: LED indicators on the front of the terminal allow for instant visual confirmation of the switching state for each of the four relays.

Technical Specifications

Frequently Asked Questions

What is the difference between switching ohmic and inductive loads with the KL2634?

Ohmic loads (like resistive heaters or lamps) have a predictable current draw. Inductive loads (like motors or relay coils) create a high-voltage back-EMF spike when switched off, which can cause arcing and prematurely wear out relay contacts. For inductive loads, the switching current capacity is reduced to 2 A to account for this stress.

Is it possible to switch 230 V AC loads directly?

Yes, the KL2634 is rated for up to 250 V AC, making it suitable for directly switching standard line-voltage devices. Always ensure you adhere to local electrical codes regarding cable separation between low-voltage signal lines and high-voltage power lines within the terminal block area.

How do the mechanical vs. electrical operating cycles work?

Mechanical cycles refer to the physical movement of the relay contact; electrical cycles refer to the load-bearing switching life. The relay will wear out faster if it is constantly switching high-current loads compared to switching a "dry" (no-load) contact.

Engineering Integration and Operational Best Practices

• Snubber/Suppression: When switching inductive loads, it is highly recommended to use an external RC snubber circuit or a flyback diode (for DC) across the load. This significantly increases the electrical operating life of the relay contacts.
• Terminal Wiring: While the module supports pluggable wiring (KSxxxx series), ensure that the ferrules are crimped correctly to the wire to ensure a gas-tight, reliable connection.
• DIN Rail Mounting: Ensure the Bus Terminal is firmly snapped into the K-bus rail. The K-bus communication between terminals occurs via side contacts; if the terminal is loose, it can lead to intermittent communication errors.
• Current Limitation: Do not exceed the 4 A current limit per channel. If your load exceeds this, use the KL2634 to switch a larger external contactor or power relay rather than driving the load directly.