Galvanic isolation is the electrical separation of two circuits such that no direct conductive path exists between them — only the signal is transferred (inductively or optically). In industrial environments, field instruments and control systems often have different ground potentials, sometimes differing by tens or hundreds of volts. Without galvanic isolation, these potential differences create ground loop currents that corrupt the 4-20 mA measurement signal with errors and noise. PR electronics isolation devices (e.g., PR 3103, PR 3108) provide 2.5 kVAC test isolation to eliminate these issues.

The PR 3103 is a 1:1 isolated repeater in PR electronics' ultra-compact slimline 6.1 mm housing. It requires no setup — simply install and it transparently passes the 4-20 mA signal with galvanic isolation. Key specifications include accuracy better than 0.05% of span, response time under 7 ms, a signal-to-noise ratio exceeding 60 dB, and a cut-off frequency above 100 Hz. At only 6.1 mm wide, approximately 163 units can be mounted per meter of DIN rail, making it ideal for high-density control cabinet installations.

The 9000-series isolation devices carry SIL 2/3 full assessment certification per IEC 61508. These include the PR 9106A (HART transparent repeater), PR 9107A (HART transparent driver), PR 9202A (pulse isolator), and PR 9203A (solenoid/alarm driver). They are designed for safety instrumented systems where functional safety certification is mandatory. The 9106A and 9107A maintain HART transparency while providing SIL-rated galvanic isolation, enabling safety systems to use HART-based smart transmitters for both process control and safety functions.

The PR 3202 accepts digital input signals from NAMUR sensors, NPN proximity switches, or dry contacts, and provides electrically isolated relay or transistor outputs. It is used to interface digital/discrete signals across isolation boundaries — for example, connecting a pulse output from a flow meter in one grounding zone to a totalizer or PLC counter in another. The device prevents ground loops on digital circuits, which can cause false counts or missed pulses. It maintains the signal timing integrity required for accurate flow measurement.

The PR 3225 is a slimline 6.1 mm programmable frequency converter that accepts multiple digital input types (NAMUR, NPN, PNP, Tacho, TTL, S0, switches) and converts them to an isolated analog mA/V output, frequency output, or relay output. It can also perform frequency-to-current, frequency-to-frequency, and frequency scaling conversions. Programming is done via the PR 4590 ConfigMate. Applications include converting turbine flow meter pulse outputs to 4-20 mA for a DCS, or scaling frequency signals between incompatible instruments.

The PR 3000-series slimline isolators are 6.1 mm wide and can accommodate approximately 163 units per meter of standard 35 mm DIN rail (EN 60715). This extreme density is a key advantage in applications requiring large channel counts in limited cabinet space, such as offshore platforms, chemical plants, and power stations. Each unit weighs approximately 70 g, so a full meter of isolators weighs about 11.4 kg. The devices clip directly onto the DIN rail without additional mounting hardware.

PR electronics isolation devices are designed and tested to exceed standard EMC requirements. The PR 3103, for example, achieves less than ±0.5% of span immunity influence under standard EMC testing, and less than ±1% of span under extended EMC testing per NAMUR NE21 criterion A. All isolation products carry CE marking per EMC directive 2014/30/EU. The combination of high galvanic isolation voltage (2.5 kVAC), signal-to-noise ratio exceeding 60 dB, and fast response times ensures that measurement signals remain clean even in environments with variable frequency drives, motor starters, and other sources of electromagnetic interference.