Elyxir Solutions · Product Datasheet

4-20 mA Loop-Powered Signal Transmitters

Convert mV signals from Ion-selective, ORP and pH electrodes to 4-20 mA format for connection to PLCs, displays, controllers, instruments and automation systems.

System Overview
Wiring diagram: electrodes → 2 transmitters → PLC

Typical wiring: electrodes → loop-powered transmitters → PLC / controller

ELIT 4-20 mA transmitters are loop-powered devices that convert high-impedance electrode mV signals into industry-standard 4-20 mA current loop signals, enabling transmission over cable runs of up to 250 metres to PLCs, data loggers, displays and process controllers.

Models are available for pH (full range 0–14 or narrow range 3.5–10.5), ion-selective electrodes, and combined pH + PT1000 temperature measurement. DIN-rail variants are also available.

All transmitters are loop-powered (no separate power supply required). Supply voltage 12–36 V DC. Maximum cable run: 250 m.
Model Comparison
Model Input pH Range Output Electrodes Max Distance Price (exc. VAT)
TRA-ISE Ion (mV, selectable range) n/a 4–20 mA 1× ISE 250 m
TRA-PHF pH (±400 mV, 0–14) 0–14 4–20 mA 1× pH 250 m
TRA-PHR pH (±200 mV, 3.5–10.5) 3.5–10.5 4–20 mA 1× pH 250 m
TRA-PHFT pH (0–14) + PT1000 temperature 0–14 4–20 mA (dual loop) 1× pH + 1× PT1000 250 m
TRA-PHRT pH (3.5–10.5) + PT1000 temperature 3.5–10.5 4–20 mA (dual loop) 1× pH + 1× PT1000 250 m
TRA-PHF-DIN pH (±400 mV, 0–14) 0–14 4–20 mA 1× pH 250 m
TRA-PHR-DIN pH (±200 mV, 3.5–10.5) 3.5–10.5 4–20 mA 1× pH 250 m
DIN-rail models (TRA-PHF-DIN, TRA-PHR-DIN) mount on standard 35 mm DIN-rail; all other models are wall-mounted.
Device Photographs
TRA-ISE device photo

TRA-ISE

TRA-PHF / TRA-PHR device photo

TRA-PHF / TRA-PHR

TRA-PHFT / TRA-PHRT device photo

TRA-PHFT / TRA-PHRT

TRA-PHF-DIN / TRA-PHR-DIN device photo

TRA-PHF-DIN / TRA-PHR-DIN

Common Specifications (all models unless noted)
ParameterStandard ModelsDIN Models
EnclosureABS, IP52ABS, IP50
Dimensions115 × 90 × 55 mm (excl. connectors)80 × 70 × 20 mm
MountingWall-mount, 4 × M4 screwsSnap-on DIN-rail
Input ConnectorBNC (50 Ω)
Reference Socket2 mm
Output4–20 mA with cable gland; screw terminals "+" and "−"
DIN Reference Terminal—Parallel screw terminal "R"
PowerLoop-powered, 12 V DC to 36 V DC
Input Impedance1 TΩ typical
Input Bias Current0.1 pA typical
Load Resistance @ 12 V< 200 Ω
Load Resistance @ 36 V< 800 Ω
Additional transmitter view

Transmitter output wiring detail

TRA-ISE — Ion-Selective Electrode Transmitter

The TRA-ISE converts the mV output from an ion-selective electrode directly to a 4-20 mA current signal. The measurement range is fully selectable: the lowest ion concentration in the monitored range corresponds to 4 mA, and the highest concentration to 20 mA.

The input range is configured via rotary switches and a trimming potentiometer, providing flexibility to match the specific ion and concentration range being measured.

For ISE electrode connections, use together with an ELIT signal amplifier for extended cable runs. See elyxir.co.uk/products for compatible amplifiers.
TRA-PHFT / TRA-PHRT — Combined pH + Temperature Transmitters

The TRA-PHFT and TRA-PHRT transmit both pH and temperature (via PT1000 sensor) simultaneously as independent 4-20 mA current loops, enabling direct connection to dual-input PLCs, data loggers or process controllers.

ParameterLoop Mapping
pH (TRA-PHFT)0–14 pH → 4–20 mA
pH (TRA-PHRT)3.5–10.5 pH → 4–20 mA
Temperature0°C = 4 mA · 100°C = 20 mA
TRA-PHFT / TRA-PHRT device photo

TRA-PHFT / TRA-PHRT — dual-output pH + temperature

Ordering & Further Information
For ISE connections use with ELIT signal amplifier — see elyxir.co.uk/products · Order direct: elyxir.co.uk/products