Emerson Electric Power Absolute Vibration Sensor (PR 9266/.. And PR 9268/..)

Emerson Electric Power Absolute Vibration Sensor (PR 9266/.. And PR 9268/..)

Sensor Overview

The PR 9266/.. And PR 9268/.. Series electric absolute vibration sensors are designed specifically for measuring the absolute vibration of machines and are part of the MMS 6000 and MMS 3000 rotating machinery monitoring systems. Its working temperature range can reach 200 ° C, using seismic function principle, easy installation, high sensitivity, sturdy structure suitable for industrial applications, with splash proof characteristics, protection level of IP 55 or IP 65, with two frequency ranges of 10 Hz to 1000 Hz and 4 Hz to 1000 Hz. When used in conjunction with safety barriers (Zone 1), the safety level is EEx ib II B/II C.

Application scenarios

The absolute vibration can be measured in frequency ranges of 10... 1000Hz and 4... 1000Hz, with vibration amplitudes of up to 2mm and 3mm (peak to peak), respectively. It can provide an electrical signal proportional to the vibration velocity. Suitable for various types of turbomachinery, fans, compressors, gearboxes, pumps, coal mills, and other machines. Among them, PR 9268/60 and PR 9268/70 are particularly suitable for high-temperature environments, such as gas turbine applications, and also include electrical adaptation, which can replace the original AEG Kanis Group's MMG 033 and MMG 1033 absolute vibration sensors, and provide three different sensor sensitivities according to the type of measurement amplifier.

Functional Principles and Design

Measurement element: composed of seismic mass blocks with coils, suspended on diaphragm springs, moving in the circular gap of permanent magnets, and guided by diaphragm springs in the longitudinal direction (measurement direction) of the measurement element.

Working mode: The sensor operates above the resonance frequency (different models have resonance frequencies between 4 and 13 Hz), while the seismic mass remains stationary. Due to the vibration of the sensor housing, an electrical signal proportional to the vibration velocity is generated.

Damping: The damping of the measuring element is achieved through a damping cylinder or external device, with a damping value of about 0.6 and good linear characteristics throughout the entire frequency range.

Special design: Measurements below the resonance frequency can be corrected by corresponding amplitude response; When the vibration amplitude is too high, the mechanical limiter will reduce the maximum amplitude of the seismic system; Each sensor is designed for a measurement direction (vertical or horizontal). The PR 9266/.. Series sensor has an additional lifting coil, which adjusts the center position of the seismic element by inputting a lifting current of up to 7mA into the coil; The PR 9268/.. Series sensors can directly input the boost current into the measurement coil, but this current must be separated from the measurement signal. The measurement amplifier of MMS 6000 supports the operation of absolute bearing vibration sensors and provides boost current.

Technical parameters

Parameter PR 9266/.. Series: PR 9268/20 and/30 PR 9268/60 and/70

Measurement principle: Low tuning system for absolute vibration measurement

Electromechanical Conversion: Electric Power, Electric Power, Electric Power

Operation direction: vertical (with lifting current), horizontal (without lifting current) PR 9268/20: ± 10 °; PR 9268/30: ± 10 ° PR 9268/60: ± 60 ° (specified data deviation ≤ 15%); PR 9268/70: ± 30 ° (specified data deviation ≤ 15%)

Frequency range:... 1000 Hz 4... 1000 Hz 10... 1000 Hz

Vibration amplitude (peak to peak) and limiter position: 2000 µ m, limiter at ± 1500 µ m 3000 µ m, limiter at ± 2000 µ m 3000 µ m, limiter at ± 2000 µ m

Natural frequency (20 ° C): Horizontal direction: 12.0 Hz ± 2 Hz; Vertical direction (lift coil activated): 12.3 Hz ± 2 Hz; Vertical direction (lift coil not activated): 14.5 Hz ± 1.5 Hz Horizontal direction: 4.5 Hz ± 0.5 Hz; Vertical direction: 4.5 Hz ± 0.5 Hz When undamped: 10 Hz ± 1 Hz; Horizontal direction: 8 Hz ± 1 Hz; Vertical direction: 8 Hz ± 1 Hz

Sensitivity and conditions: 30 mV/mm ⁻¹ at 50 Hz, 20 ° C, and 100 kOhm load; 28.5 mV/mm ⁻¹ at 50 Hz, 20 ° C, and 100 kOhm load; 22 mV/mm ⁻¹ at PIN 3 and 100 kOhm load; 16.7 mV/mm ⁻¹ at PIN 1 and 50 kOhm load; 16.7 mV/mm ⁻¹ at PIN 4 and 20 kOhm load

Tolerance: ± 3%<± 5.25% ± 5%

Linear error:<2%<2%<2%

Lateral sensitivity:<0.03 (at 50 Hz) PR 9268/20:<0.27; PR 9268/30:<0.13 (at 110 Hz)<0.1 (at 80 Hz)

Damping coefficient (20 ° C/100 ° C): approximately 0.6/approximately 0.43, approximately 0.56/approximately 0.42, measured at PIN 3, approximately 0.7/approximately 0.5 (at 200 ° C)

Effective capacitance (including cable):<2.5 nF<1.2 nF<2.0 nF

Measurement of coil electrical data (DC resistance/inductance): 1800 Ohm ± 12% (including calibration coil); Measurement coil ≤ 62 mH, lifting coil ≤ 75 mH 1875 Ohm ± 2% (including internal resistance); ≤68 mH PIN 3：2760 Ohm±10%； PIN 1：3260 Ohm±10%； PIN 4：3180 Ohm±10%； ≤200 mH

Allowable acceleration (measurement direction/lateral): 10 g continuous, 20 g short-term/5 g 10 g continuous, 20 g short-term/2 g 10 g continuous, 20 g short-term/2 g