Inductive and capacitive sensors - INFRA - #1

FRA

Inductive and Capacitive Sensor

GENERAL SPECIFICATIONS

It is the precision by which the sensor switching commutation distance is repeated at the maximum supply voltage, at the temperature of 23 °C ± 5 °C with a load current = 100 mA, during a 8 hours period.

The value expresses the percentage of the difference between the maximum and the minimum measure related to the average value of the switching distance Sn.

It is the maximum possible number of impulse repetition per second. This value is obtained by measurement with a cogged wheel in which cogs are of triggering material. The cogs are as large as the diameter of the sensor and the distance between two cogs is twice the diameter (according to the EN 60947-5-2).

Voltage to the device creates an alternate inductive field through an oscillator coil before its active surface. If a metallic object (iron, alluminium, cooper, brass etc.) enters this field, it damps the oscillator and reverses the trigger threshold and causes a change in the output stage state.

Capacitive sensors contain an oscillator by transistor in the frontal section. The oscillating circuit R - C (Resistor - Capacitor) is influenced by variations in capacity, infact when any material, solid or liquid (water, wood, metal, caffee, ponders, etc) comes into contact with the active surface of the sensor the capacitance increases putting into action the oscillator up until the threshold of trigger inverts. By introducing a change in the condition of the final stage and therefore in the command of the external load a potentiometer makes fine adjustment to switching distance.

It is the conventional distance at which the proximity switches when approching standard targets with axial movement. Such target (conform to the EN 500 10 regulation) shoud be of steel Fe37, square and 1mm thick. Targets should be the same as the sensor diameter.

It indicates the power supply where the sensor works perfectly. RESIDUAL RIPPLE

Maximum ripple allowed on supply DC voltage. It is shown in percentage referring to the medium value.

The maximum output current of the sensor in continuous operation. MINIMUM OUTPUT CURRENT

Minimum output current through the sensor to maintain normal operation. MAXIMUM PEAK CURRENT

The maximum current the sensor can sustain in a limited period of time.

It is the assured operating distance within the specified voltage, functionning and temperature intervals it is included between 81% and 121% of the nominal switching distance Sn (0,81Sn < Su < 1,21Sn) for inductive sensors, and between 72% and 132% of the nominal switching distance (0,72Sn < Su < 1,32Sn) for capacitive sensors.

It is the distance at which the proximity sensor works safely in all the temperature and voltage intervals as specified for the same sensor. The assured operating distance is included between 0 and l'81% of Sn (0 < Sa < 0,81Sn) for inductive sensors, and 0 and 72% of Sn (0 < Sa < 0,72Sn) for capacitive sensors.

When the element to be detected is different from Fe37, reduction factors are:

All the sensor with DC supply are protected against reversal of polarity, this prevents the internal components from being damaged by incorrect power supply connection.

It protects sensor output in presence of high inductive loads. This protection is performed by a diode or zenner diod. If possible keep the power conductors separate.

The degree of protection of the housing and conform to the IEC 529 regulation.

Time interval between sensor supply connection and active output.

It is the distance between the point of switching on and the point of switching off of the trigger object. The value is a percentage of the nominal switching distance Sn.

OFF ,'/ ON

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