Quad Current Loop Splitters

Laureate QLS-1 and QLS-2 Quad Output 4-20 mA Current Loop Splitter / Retransmitter

What is the Laureate QLS Quad Output 4-20 mA Current Loop Splitter / Retransmitter?

The Laureate QLS is a DIN rail-mounted signal splitter that accepts a single 4-20 mA, 1-5V, 0-5V, or 0-10V input and drives four fully independent 4-20 mA output loops. It solves one of the most common problems in industrial instrumentation: the limitations of wiring multiple devices in series on a single current loop.

In a traditional series loop, all connected devices — a panel meter, a PLC input, a recorder, and a control valve, for example — share the same current path. If any one device fails, is removed, or develops a wiring fault, every device on that loop loses its signal. Devices cannot share a common ground, and the voltage compliance of the transmitter may be exceeded as load voltage drops add up in series.

The QLS eliminates these problems by splitting one input into four independently driven output loops, each galvanically isolated from the others and from the power supply. Opening one output loop has no effect on the remaining three.

QLS-1 vs. QLS-2: Choosing the Right Power Option

The QLS is available in two models that are identical in signal performance and differ only in power supply input:

• QLS-1 — powered by 85-264 Vac or 90-300 Vdc. Suited for standard industrial AC power environments.
• QLS-2 — powered by 10-48 Vdc or 12-32 Vac. Suited for low-voltage DC systems, battery-backed installations, and applications where 24 Vdc panel power is standard.

Both models provide a 24 Vdc excitation output to power a 2- or 3-wire input transmitter at up to 30 mA, making the QLS a self-contained signal distribution point that can power the upstream sensor as well.

Key Features

• Four independent 4-20 mA output loops from one input
• ±10V common mode isolation — output ground references can differ by up to ±10V from local signal ground
• ±10% zero and span adjustment per output loop via 25-turn potentiometers
• Loop current test point per output — 200 mV = 20 mA, measurable with a standard multimeter without breaking the loop
• Yellow LED per output loop indicates continuity; brightness proportional to current
• Accuracy of ±0.02% max span error at 23°C
• Response time of 2 ms rise, 7 ms settling to 0.1% of final value
• 22.5 mm wide DIN rail case, operating from -40°C to 70°C
• ETL, CE, and RoHS 3 certified
• Factory calibrated; annual recalibration recommended

Where is the Laureate QLS Quad Current Loop Splitter Used?

The QLS is used anywhere a single 4-20 mA transmitter signal needs to drive multiple devices simultaneously without the reliability and grounding problems inherent in series wiring. Common applications include:

1. Process Control with Multiple Receiving Devices

When a flow meter, pressure transmitter, or temperature sensor must feed a panel meter, a PLC analog input, a data logger, and a chart recorder simultaneously, the QLS provides four isolated outputs from that single sensor. Each device operates independently — a failed PLC input card does not affect the panel meter or recorder.

2. Replacing Series Loop Wiring in Existing Installations

Many older installations wire process devices in series. When loop reliability becomes a problem — or when adding a new device would exceed the transmitter's voltage compliance — the QLS provides a straightforward retrofit solution without replacing field wiring or transmitters.

3. Distributing Signals Across Different Ground References

In large facilities, ground potential differences between control rooms, field panels, and equipment cabinets are common. The QLS's ±10V common mode isolation allows output loops to reference different local grounds without creating ground loops or corrupting the signal.

4. Powering Remote Transmitters from the Control Panel

The 24 Vdc excitation output allows the QLS to power a 2- or 3-wire field transmitter directly, eliminating the need for a separate loop power supply. This simplifies wiring and reduces panel component count.

5. Calibration and Diagnostics in Multi-Drop Systems

Each output loop's individual zero/span adjustment and current test point make it easy to calibrate each receiving device independently and verify loop current with a multimeter in the field — no loop interruption required.

Conclusion

The Laureate QLS-1 and QLS-2 Quad Current Loop Splitter / Retransmitter provides a reliable, compact, and diagnostics-ready solution for distributing 4-20 mA signals to multiple devices. Its isolated outputs, per-loop adjustability, and LED diagnostics make it a practical upgrade over series loop wiring in any industrial instrumentation system.