LD400 Miniature, LVDT Linear Position Sensors

Supported Applications

The Omega LD400 series consists of miniature DC output linear variable displacement transducers (LVDTs) designed to measure displacements up to ±5.0 mm (±0.20"). These self-contained units accept a regulated DC input and provide a DC voltage output relative to armature position, utilizing hybrid ICs including an oscillator, demodulator, and filter. The series is engineered for applications in civil, mechanical, chemical, and production engineering where high linearity and low mass of moving parts are required.

Operating Conditions & Performance

The LD400 transducers operate within a compensated temperature range of -20 to 80°C (-4 to 176°F). The series delivers an accuracy (linearity) of 0.3% FS and features infinite resolution for detecting the smallest movement identifiable by associated instrumentation. Electrical performance includes an excitation requirement of 10 to 24 Vdc regulated, with a frequency response of 50 Hz at -3 dB and ripple less than 1% FS.

Response time varies by model stroke: LD400-1 and LD400-2.5 models exhibit a 5 ms response time, while the LD400-5 model provides a 3 ms response time. Thermal effects on zero are specified as less than 0.02% FS/°C for the LD400-1 and less than 0.01% FC/°C for the LD400-2.5 and LD400-5; sensitivity thermal drift is less than 0.025% FC/°C.

Configuration Options

The series offers three distinct stroke configurations, each with specific dimensions and weights:

• LD400-1: ±1.0 mm (±0.04") stroke; 75 mV/V/mm sensitivity.
• LD400-2.5: ±2.5 mm (±0.10") stroke; 75 mV/V/mm sensitivity.
• LD400-5: ±5.0 mm (±0.20") stroke; 54 mV/V/mm sensitivity.

Mechanical construction features a free-guided armature with acetal bearings to provide near-frictionless motion. The case material is 400 Series stainless steel, and the core utilizes Ni/Fe—Radio Metal 50. Each unit includes an M2 threaded core for connection.

Key Product Differences

The primary distinction among models lies in stroke length, which influences sensitivity values and physical dimensions. The LD400-1 and LD400-2.5 share identical body weights of 26 g (1.02 oz) and core weights of 1.0 g (0.04 oz), with overall dimension A at 21.5 mm (0.85 in). The LD400-5 model has a slightly shorter diameter (A: 20.5 mm / 0.81 in) but increased length and weight, totaling 30 g (1.18 oz) for the body.

Electrical connections are provided via a 2.9 m (9') shielded, color-coded cable with specific pinouts: Red (+ Excitation), Blue (- Excitation), White (+ Signal*), Green (- Signal), and Yellow (No connection). The white signal wire is in phase for positive inward displacement.