Special shaped rotor and wound coil to achieve high reliability and performance

About the R30A RVDT

The R30A RVDT (Rotary Variable Differential Transformer) is an angular position sensor that incorporates a proprietary non-contact design which dramatically improves long term reliability when compared to other traditional rotary devices such as synchros, resolvers and potentiometers. This unique design eliminates assemblies that degrade over time such as slip rings, rotor windings, contact brushes and wipers, without sacrificing accuracy.

High reliability and performance are achieved through the use of a specially shaped rotor and wound coil that together simulates the linear displacement of a Linear Variable Differential Transformer (LVDT). Rotational movement of the rotor shaft results in a linear change in the amplitude of the output signal, directly proportional to the shaft angle change, while the phase of this output signal indicates the direction of displacement from the null point. Non-contact electromagnetic coupling of the rotor provides infinite resolution thus enabling absolute measurements to a fraction of a degree.

AC operation eliminates the need for integrated signal conditioning components, thereby offering the user an extremely wide operating temp. range of -55°C to +150°C. Factory calibrated to operate over a ±30 degree range, the R30A offers a non-linearity of less than ±0.25% of full range. Extended range operation up to a maximum of ±60 degrees is possible with increased non-linearity. Packaged in a small, size 11 servo mount, aluminum housing with flying lead termination, the R30A is ideal for space restrictive applications.

Also see our other angular position sensor models, R36AS (stainless steel housing, MS style connector), RSYN (high output, shock and vibration tolerant), R30D and R60D (bipolar DC operation), and the RVIT-15 Series (single ended DC operation, voltage or current output).

Features R30A

  • High accuracy
  • Infinite resolution
  • Long term reliability
  • Wide -55º to +150ºC operating temp range
  • Rugged anodized aluminum housing
  • Shielded ABEC 3 precision bearings

Applications for R30A

  • Valve position
  • Machine tool equipment
  • Rotary actuator feedback
  • Dancer arm position
  • Process control


Output at range ends (*)
87mV/V, 116mV/V, 174mV/V
2.9 mV/V/degree
Temp coefficient of sensitivity
0.02%/ºF [0.036%/ºC], 20 to +160ºF [-7 to +71ºC]
Input / Output impedances
370O / 1300O
Phase shift
Input voltage and frequency
3 VRMS @ 2.5 to 10 kHz (10kHz recommended)
Null voltage
0.5% of FRO, maximum
Mechanical angular range
360 degrees (no stops)
Shielded ABEC 3 precision
Housing material
Aluminium, anodized
Size 11 servo mount per BU-ORD
Moment of inertia
0.53 x 10-6 inch.lb-force.second2 [0.61 x 10-6 Kg-force.cm.second2]
  • Follow us: