DT-121

Supported Applications

The Omega DT-12x series is a non-contacting integrated displacement transmitter based on the eddy current measurement principle. It measures the distance between the transmitter tip and an electrically conductive surface, providing output for either radial shaft vibration (RV) or axial shaft position (AP). The device features forward and reverse mount versions to accommodate specific installation geometries.

Operating Conditions & Performance

The series operates within an ambient temperature range of -40 °C ... +105 °C, with a storage temperature range of -55 °C ... +125 °C. The transmitter tip is rated for 25 bar pressure tightness; the DT-122 variant with corrugated tube protection also supports 25 bar. Enclosure ratings are IP68 and IP69.

Performance specifications vary by measurement mode:

• Radial shaft vibration (RV): Accuracy is ±0,2 % from full scale (FS) at 0 °C ... +45 °C and ±0,5 % (FS) over the overall operating temperature range. Sensitivity accuracy is ±5 % (0 °C ... +45 °C) or ±10 % (overall). The loop frequency range is 5 Hz ... 4 kHz with a refresh time of 15 ms.
• Axial shaft position (AP): Accuracy deviation from the best fit straight line is ±25 µm at 0 °C ... +45 °C and ±75 µm over the overall operating temperature range. The loop frequency range is DC ... 0,8 Hz with a refresh time of 100 ms.

Dynamic output provides a nominal sensitivity of +8 mV/µm across a frequency range of DC ... 8 kHz (-3 dB output signal damping). Accuracy for dynamic output is ±5 % (0 °C ... +45 °C) and ±10 % over the overall operating temperature range.

Configuration Options

The series supports multiple measurement ranges, outputs, and mechanical configurations. The model number structure follows DT-12x.<HOUSING>.<MEASUREMENT>.<CABLE>.<PROTECTION>.<LENGTH>.<VERSION>.

• Measurement Ranges:

Radial shaft vibration (RV) ranges include 0 - 100 µm peak-to-peak, 0 - 250 µm peak-to-peak, and 0 - 600 µm peak-to-peak. Equivalent mils ranges are 0 - 4 mils peak-to-peak, 0 - 10 mils peak-to-peak, and 0 - 24 mils peak-to-peak.

Axial shaft position (AP) ranges include 0 – 1,2 mm and 0 – 1,5 mm. Equivalent mils ranges are 0 – 50 mils and 0 – 60 mils.

• Output Signals:

The loop output provides a 4 - 20 mA live-zero signal compliant with NAMUR Recommendation 43 for signaling range overshoot or error. A dynamic output of +8 mV/µm is available, though it is not designed for continuous operation and supports limited cable lengths (max. 15 m including integrated length).

• Power & Electrical:

The device requires a power supply of +24 VDC (+12 VDC ... +32 VDC) with a maximum current consumption of 21 mA. The electrical connection is a 4 wire cable with PTFE, black sheath (Ø 2,9 mm ±0,15 mm). Wire assignments are white/black for the loop and red/blue for dynamic output.

• Materials & Construction:

The transmitter tip is ceramic with a diameter of Ø 7,2 mm (± 0.1 mm). The sleeve material is Stainless steel (Material-No.1.4404 X2CrNiMo17-12-2 nach EN10088-3) with a recommended tightening torque of 5 Nm.

• Options & Accessories:

Variants include the DT-121... (without cable protection, with steel protective conduit, or with PTFE protective conduit) and the DT-122... (with pressure-tight corrugated tube protection design A or B).

Key Product Differences

The series distinguishes between two primary measurement functions defined in the model code: Radial shaft vibration (RV) for dynamic monitoring with a 5 Hz ... 4 kHz frequency range, and Axial shaft position (AP) for static or low-frequency positioning with a DC ... 0,8 Hz range. Mechanical variations include cable lengths of 5 m or 10 m and different protective conduit options.

Installation requires gapping the transmitter from the target (shaft) between +2V to +18V output voltage, corresponding to a distance greater than 0.5mm and less than 2.5mm. The dynamic output is short circuit proof and miswiring proof but limited by cable capacity of max. 150 pF/m.