Pepperl+Fuchs KCD2-SR-2 2-Channel Relay Switch Amplifier

KCD2-SR-2 two-channel relay switch amplifier for NAMUR sensors

The KCD2-SR-2 transfers two digital signals from NAMUR proximity sensors or dry contacts to two relay outputs. It isolates the field circuit from the control circuit, monitors the sensor cable for breaks and short circuits, and fits two channels into a 12.5 mm housing. It is the economical choice for limit switch, position and status signals that are wired to relay-based or PLC inputs.

Seven Star LLC supplies the KCD2-SR-2 in Oman and the GCC as an independent supplier in Muscat. This page gives the specification, the behaviour on fault and the guidance for ordering.

KCD2-SR-2 designation

The KCD2-SR-2 belongs to the narrow 12.5 mm K-System housing family, and the datasheet names it a switch amplifier, a 2-channel signal conditioner with 24 V DC supply through the Power Rail. Its sibling KCD2-SOT-2 has transistor outputs instead of relays.

The datasheet lists SIL 2 and systematic capability SC 3 according to IEC/EN 61508, and an input compliant with EN 60947-5-6 (NAMUR). The ambient temperature range is -40 to 70 °C.

Technical specifications of the KCD2-SR-2

How the KCD2-SR-2 switches and supervises

Each input supplies a small current to a NAMUR sensor and watches the current: between roughly 1.2 and 2.1 mA the output state changes, with a hysteresis of about 0.2 mA. The same current monitoring detects a cable break (at or below 0.1 mA) and a short circuit (6.5 mA or more), and in either case the relay drops to its de-energized state while the LEDs show the fault according to NAMUR NE 44.

DIP switches reverse the mode of operation per channel, which lets the module give a normally-open or normally-closed behaviour regardless of the sensor type, and they can switch the line fault detection off when a plain mechanical contact is used without resistors. A collective error is passed to the Power Rail when the module is fed from it.

The relay contacts can switch up to 250 V AC at 2 A, which allows direct control of small contactors and signal lamps, though the minimum switching current of 2 mA at 24 V DC must be respected for low-level signals.

Where the KCD2-SR-2 is placed in a panel

The module belongs in the safe area for non-intrinsically safe sensors. It sits next to the KCD2-SOT-2 for transistor outputs, the KFD2-SR2-Ex2.W for intrinsically safe sensors from hazardous areas and the KFD2-RSH-1.2E.L3 for load-switching duty.

Use the Power Rail with the KFD2-EB2 power feed module to avoid daisy-chaining supply wires across a long row of narrow modules.

Selection and ordering checklist for the KCD2-SR-2

• Number of channels and sensor type (NAMUR or dry contact)
• Required relay behaviour per channel
• Load on the relay and minimum current
• Whether line fault detection is wanted for each channel
• SIL requirement
• Supply and rail arrangement

Installing the KCD2-SR-2

For a dry contact, fit the resistors indicated in the connection diagram of the datasheet so that the line fault detection can distinguish a closed contact from a short. Set DIP switches according to the desired logic before connecting loads.

In commissioning, operate each sensor and check the relay and LED, then simulate a cable break and check that the relay de-energizes. With 12.5 mm modules, label each channel clearly.

Typical applications in Oman and the GCC

Limit switch and valve position feedback, pump run signals, level switch inputs, and door and guard status are typical signals. The module is common in oil and gas skids, desalination valve galleries and water treatment panels. When the relay contacts switch inductive loads such as small contactor coils, the usual suppression elements should be fitted across the load to protect the contacts and to keep electrical noise away from neighbouring narrow modules.

Switch amplifiers from the same family

From the datasheets.

Information to send with an RFQ for the KCD2-SR-2

Send the following.

• Sensor type and how many channels are needed
• Output type (relay or transistor)
• Load rating
• Quantity and delivery date

Site conditions in Oman for the KCD2-SR-2

Control cabinets in Gulf plants often run hot, because many sit in outdoor kiosks or in rooms where air conditioning is not always reliable. Before you finalise the KCD2-SR-2, check the permitted ambient range and any derating stated by the manufacturer against the real temperature inside your panel, and leave the recommended spacing around the device so that heat can escape. Long cable runs between the field and the marshalling cabinet are common on large sites, so confirm the signal types, wiring limits and earthing arrangement early in the design.

It also helps to standardise on a small number of part numbers across a project. Keeping a few spare KCD2-SR-2 units on site in Oman shortens recovery time after a fault, and documenting configuration settings makes replacement faster for the maintenance team.

Documents and quotation

The manufacturer datasheet for the KCD2-SR-2 is attached on this page, so the electrical data, terminal assignment and ambient limits quoted above can be checked against the original document before an order is placed.

Seven Star LLC supplies Pepperl+Fuchs products in Oman and the GCC as an independent supplier in Muscat. Send the quantity, the signal types and the project delivery date, and we will confirm availability and lead time in a written quotation.