Shaft position and speed sensors

omron-e3fa-dn12Each vibrometer-balancer ТСТ 2301  includes a set of accessories for measuring the speed, carrying out phase measurements and balancing, consisting of:
speed sensor OMRON E3FA-DN12,
– the fastening point of the speed sensor on the magnetic holder;

The speed sensors can be of two types: the optical speed and phase sensor  OMRON E3FA-DN12 and tachometry eddy current sensor inductive cylindrical proximity sensor of PR18 series.

The optical speed sensor has a threaded connection and can be attached to both the holder and the mounting stand or to a special magnetic stand.

The optical sensorрreacts to the change in the reflection coefficient of the shaft surface. The sensor provides a positive signal of a rectangular shape with an amplitude equal to the supply voltage of the sensor (5-10 V) and a duration of 1 msec or more when the mirror reflective mark passes the sensor end face at a distance of up to 150 mm. Range of speeds of rotation of the machine from 120 to 18000 rpm.

The OMRON E3FA-DN12 optical sensor has an adaptive gain adjustment, which ensures that the sensor response is captured and held on the most reflective part of the shaft surface. This circumstance makes it possible to use a sensor to measure the rotation speed of an object even without installing a special reflective marker , and also significantly reduces the label quality requirements for phase measurements or balancing. For a reliable grip, it is sufficient to change the reflection coefficient of the surface by 15-20%.  Practically in 8 cases out of 10 marks are not required at all, therefore it is possible to carry out phase measurements and measurements of the shaft rotation frequency without stopping the equipment.

The OMRON E3FA-DN12 sensor is protected from direct exposure to artificial light sources (incandescent lamps, fluorescent lights) to the light receiving elements of the sensor. So, the direct illumination from a 60 W incandescent lamp from a distance of 500 mm does not lead to a malfunction of the sensor.

Вихретоковый-датчик-тахометрииThe eddy current sensor PR18  reacts to the distance between the end face of the sensor and the surface of the rotating shaft or other electrically conductive elements of the rotor of the machine. To ensure the stable operation of the eddy current sensor PR18  on the shaft of the controlled machine, you must select or set a mark that is a metal ledge or groove in the shaft metal (for example, keyway). When the mark passes past the end face of the sensor, the latter generates an electric rectangular positive pulse with an amplitude equal to the sensor supply voltage (5-15 V) and a duration determined by the passing time of the mark past the sensor. With linear mark sizes of the order of 10-20 mm, the distance between the sensor and the mark can be up to 5 mm. Eddy current sensors have two modifications: for working with a projection and for working with a groove.

The speed range of the machine is from 20 to 50,000 rpm. A special sensor was also developed to operate at speeds up to 200,000 rpm.

The eddy current sensor has an automatic adjustment that compensates for the influence of the metal components of the machine structure located near the end surface of the sensor and creates a constant background during its operation.


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