LDX-2 LVDT Signal Conditioner, Loop Powered for AC LVDT

 Supported Applications

The Omega LDX-2 is a loop-powered signal conditioner designed for use with inductive-type AC LVDT displacement transducers. It functions as an onboard oscillator to drive the transducer primary winding and includes amplifier, demodulator, and filter circuits that condition the output into a milliamp current drive. The transmitter is suitable for applications requiring substantial distances between the transducer and controller or computer within automated manufacturing processes.

The series supports compatibility with most Omega LD200 & 300 series AC LVDT transducers. It provides selectable gains and transducer configurations to accommodate calibration requirements across various displacement ranges.

Operating Conditions & Performance

The LDX-2 operates within an ambient temperature range of 0 to 70°C (32 to 158°F) with a storage temperature capability from -40 to +80°C (-40 to 176°F). The unit is housed in grey ABS impact-resistant plastic and sealed to NEMA 12 (IP65), designed to withstand low-pressure water hosing when lid and cable entry seals are properly applied.

Performance specifications include a second-order linearity of better than 0.02% and an output ripple less than 50 μA p-p @ 10 kHz. The frequency response features a cutoff at -3 dB @ 25 Hz with critical damping. Long-term stability is typical at 0.2%/year for zero and 0.3%/year for gain, while temperature coefficients are better than 0.01% FS/°C for both zero and span.

Configuration Options

The LDX-2 series offers configurable electrical outputs and transducer drive settings to match specific LVDT models:

• Output Signals: 4 to 20 mA (2-wire) or 0 to 20 mA (3-wire).
• Power Supply: 13 to 48 Vdc, up to 30 mA. The supply is protected internally against reversed connections.
• Transducer Drive: 0.9V rms at 5kHz nominal with a switchable option for 13 kHz.
• Sensitivity Range: Supports transducers from 30 to 530 mV/V in two coarse gain positions, with an adjustable range of zero control up to 100% on maximum gain and a switched/adjustable gain ratio of 3.5:1 / 5:1.
• Mounting: Includes through holes for mounting via screws and nuts; also supports DIN 46277-1 rail installation with supplied accessories (two fixing screws and two nuts).

The unit features seven screw terminals accessible through two cable ports designed for wires ranging from 1 to 5 mm (0.04 to 0.2") diameter.

Measurement Ranges by Transducer Model

Usable displacement ranges vary based on the specific LD200 or LD300 transducer model, gain setting (Low/High), and output type:

• LD200-1.25: ±0.4 to 2.9 mm (4-20 mA Low Gain) / ±0.1 to 0.6 mm (4-20 mA High Gain).
• LD200-2.5: ±0.5 to 2.5 mm (Low Gain) / ±0.1 to 0.7 mm (High Gain).
• LD200-5: ±1.0 to 5.2 mm (Low Gain) / ±0.3 to 1.5 mm (High Gain).
• LD200-7.5: ±2.1 to 10.4 mm (Low Gain) / ±0.6 to 2.9 mm (High Gain).
• LD200-10: ±3.9 to 19.3 mm (Low Gain) / ±1.1 to 5.5 mm (High Gain).
• LD300-15: ±3.1 to 15.6 mm (Low Gain) / ±0.9 to 4.4 mm (High Gain).
• LD300-25: ±5.3 to 26.5 mm (Low Gain) / ±1.5 to 7.5 mm (High Gain).
• LD300-50: ±11.4 to 57.0 mm (Low Gain) / ±3.2 to 16.1 mm (High Gain).
• LD300-100: ±21.2 to 106.0 mm (Low Gain) / ±6.0 to 30.0 mm (High Gain).
• LD300-250: ±14.2 to 71.4 mm (Low Gain) / ±50.5 to 252.4 mm (High Gain).

Note: The upper gain limit is set by the transducer stroke; for example, an LD200-1.25 has a practical limit of ±1.25mm despite electronics allowing wider ranges.

Key Product Differences

The LDX-2 series distinguishes itself through its loop-powered architecture and specific compatibility with AC LVDTs, differentiating it from DC-excited or voltage-output conditioners. The device offers two distinct output configurations: a 4 to 20 mA signal in a 2-wire configuration and a 0 to 20 mA signal in a 3-wire configuration.

Configuration for specific transducer models is achieved via internal switch settings (SW1 through SW8) as defined by the manufacturer's table, allowing selection of gain and range parameters without external programming tools. The unit includes open and short circuit protection on both the oscillator and output circuits to safeguard against wiring faults.