Shiva Electronics

Panchavati, Nashik, Maharashtra

Slot Sensors also called as Fork Switches because of their forked shape, detect objects that pass between the two arms one is the Transmitter & the other is the Receiver. These sensors operate on a through beam design, they combine the transmitter & receiver into a fixed housing so alignment is never an issue. The transmitter emits pulsed light in the infrared wavelength range. The receiver detects the light beam and immediately converts a beam interruption caused by an object in the sensing zone into a switched signal. Fork Width is defined as the height between the transmitter & receiver. Depth is defined as the distance between the transmitter & receiver area and back of the opening.

In all automated processes sensors are absolutely necessary to provide the PLC with information. They supply the necessary signals on positions, limits or serve as pulse pick-ups for counting tasks or for monitoring rotational speed. Inductive & Capacitive Proximity Switches are useful in industries for non-contact operation free from any wear & tear with high switching frequencies and accuracy. They are insensitive to vibration, dust & moisture. Inductive Sensors detect all metals without contact. Capacitive Sensors detect almost all solid and liquid media such as metal, glass, wood, plastic, water, oil etc.

Inductive Proximity Switches take advantage of the physical effect of the change in the quality factor in a resonant circuit caused by eddy current losses in conductive materials. This is how it works: ALC tuned circuit generates a high frequency electromagnetic field. This field is radiated from the active face of the oscillator. This reduce the oscillation amplitude. The change is converted into a switching signal. The operating principle permits detection of all metals irrespective of whether they are moving or not. Important: the high frequency field causes no measurable heat in the object nor is there any magnetic interference. The operation of the sensors is without interaction.
The distance to the active face at which an electrically conductive material causes a change of signal in the sensor is called sensing range. The sensing range of an Inductive Proximity Switch is defined by means of a target of mild steel (Fe 360). If the switch is damped by other metals, e.g. aluminium or copper, this is reduced. Using correction factors for every kind of metal the user can calculate the attainable sensing ranges.

An "absolute" encoder maintains position information when power is removed from the system. The position of the encoder is available immediately on applying power. The relationship between the encoder value and the physical position of the controlled machinery is set at assembly; the system does not need to return to a calibration point to maintain position accuracy. An "incremental" encoder accurately records changes in position, but does not power up with a fixed relation between encoder state and physical position. Devices controlled by incremental encoders may have to "go home" to a fixed reference point to initialize the position measurement. A multi-turn absolute rotary encoder includes additional code wheels and gears. A high-resolution wheel measures the fractional rotation, and lower-resolution geared code wheels record the number of whole revolutions of the shaft.

An incremental rotary encoder provides cyclical outputs (only) when the encoder is rotated. They can be either mechanical, optical or magnetic. The mechanical type requires denouncing and is typically used as digital potentiometers on equipment including consumer devices. Most modern home and car stereos use mechanical rotary encoders for volume control. Due to the fact the mechanical switches require denouncing, the mechanical type are limited in the rotational speeds they can handle. The incremental rotary encoder is the most widely used of all rotary encoders due to its low cost and ability to provide signals that can be easily interpreted to provide motion related information such as velocity.

The fact that incremental encoders use only two sensors does not compromise their resolution. One can find in the market incremental encoders with up to 10, 000 counts per revolution, or more.

There can be an optional third output: reference or "index", which happens once every turn. This is used when there is the need of an absolute reference, such as positioning systems. The index output is usually labelled Z.

The optical type is used when higher speeds are encountered or a higher degree of precision is required. Incremental encoders are used to track motion and can be used to determine position and velocity. This can be either linear or rotary motion. Because the direction can be determined, very accurate measurements can be made.

Microcontroller based Power Pack Module is used to generate On and Off delay in the output set by user after any input changed is sensed by sensor interfaced to module. User can adjust delay (Range from 0-9 seconds) using switches S1 and S2 provided on board, corresponding delay also be seen on seven segment display. PNP and NPN both type of sensor can be connected to module, depending on the user set delay value Thyristorised output is generated which can be used to control AC load connected to module