Relay Electromagnetik a Yi Kwado | Abubuwa na Relay Electromagnetik
Reli Maitoita
Reli maitoita suna da suka amfani da toitoci mai maitoita. A yanzu, manyan relis kiyaye masu hanyar na'ura suna da muhimmanci, amma reli maitoita tana ciki a matsayin wata. Zai ya dacewa da lokaci mai kyau don bayyana duk relis maitoita da microprocessor. Saboda haka, idan muna neman cikakken bayanan jamiyar relis, yawanci na iya duba cikin manyan types of electromagnetic relays.
Muhimmiyar Tattalin Reli Maitoita
Duk abubuwan da suke amfani da su a kan tattalin relis suna da wata ko kadan daga cikin manyan types of electromagnetic relays.
Tattalin tsari,
Tattalin ziyartar,
Tattalin tsarin tsari.
Muhimmin tattalin reli maitoita suna da al'adun da ke gaba. Kafin a duba cikin al'adun, za a iya koyar da su zuwa manyan types of electromagnetic relays.
Wata na armature,
Wata na disc induction,
Wata na cup induction,
Wata na beam balanced,
Wata na coil moving,
Wata na polarized moving iron.
Wata na Armature Attraction
Wata na armature attraction shine wata mafi so kuɗi a cikin kimiyyar da tattalin. Wannan wata na relis maitoita zai iya amfani a matsayin wata na tsari ko wata na tsarin tsari. Su ne suka amfani a matsayin relis kiyaye, relis kudin, relis over current, under current, over voltage, under voltage da kuma relis na measurement impedance.
Kimiyyar hinged armature da plunger type suna da muhimmanci a kan wannan types of electromagnetic relays. Daga labar kimiyyoyi, hinged armature type shine mafi amfani a yanzu.
Ana san shi cewa lagamun da ke faruwa a kan armature shine mafi tsari da karamin kasa na magnetic flux a kan air gap. Idan muna baƙi ƙungiyar saturation, za a iya bayyana lagamun da armature ke faruwa a matsayin,
Idan, F shine net force, K’ shine constant, I shine rms current na armature coil, da K’ shine restraining force.
Sharti na farko don tattalin relay yana iya samun idan KI2 = K’.
Idan muna duba taƙardun da tana iya ba da shiga, ana yi fahimta cewa tattalin relay yana da nasara ga constants K’ da K don ɗaya ɗaya na coil current.
Daga bayanin da tana iya bayyana da tashen, ana iya haɗa cewa, tattalin relay yana da nasara ga
Ampere – turns developed by the relay operating coil,
The size of air gap between the relay core and the armature,
Restraining force on the armature.
Kimiyyar Wata na Armature Attraction
Wannan reli shine wata electromagnetic coil, da hinged plunger. Idan coil an yan, plunger ya ƙarewar da core na coil. Akwai NO-NC (Normally Open and Normally Closed) contacts suna da su kamar haka, inda NO contacts zai ƙare, da NC contacts zai bude saboda ƙarewar plunger. A yanzu, wata na armature attraction shine DC operated relay. Contacts suna da su kamar haka, inda ba a iya bude ba su da ƙarewar armature. Ba tattalin relay, types of electromagnetic relays suna reset manually.
Wata na armature attraction, saboda kimiyyar da tattalinsa, yana ƙare instantaneous
a tattalin.
Wata na Disc Induction
Wata na disc induction shine wata na disc mai ƙare.
Tattalin Wata na Disc Induction
Duk wata na disc induction suna da tattalin da ke gaba da Ferrari’s principle. Wannan principle yana ce, torque yana faruwa saboda phase displaced fluxes, wanda yake da tsari da phase displacement daga baya. Mathematically it can be expressed as-
Wata na disc induction yana da tattalin da ke gaba da ammeter ko volt meter, ko wattmeter ko watt hour mater. A cikin induction relay, deflecting torque yana faruwa saboda eddy currents a cikin aluminium ko copper disc da AC electromagnet. Hakan, an saka aluminium (ko copper) disc a kan poles na AC magnet wanda yake faruwa alternating flux φ lagging from I by a small angle. Idan flux na yana ƙare da disc, yana da inda emf E2 a cikin disc, lagging behind the flux φ by 90o. Idan disc yana da resistance, induced current in the disc I2 will be in phase with E2. As the angle between φ and I2 is 90o, the net torque produced in that case is zero. As,
In order to obtain torque in induction disc type relay, it is necessary to produce a rotating field.
Yadda A Faruwa Torque a Cikin Wata na Disc Induction
A cikin wannan hanyar, half of the pole is surrounded with copper ring as shown. Let φ1 is the flux of unshaded portion of the pole. Actually total flux divided into two equal portions when the pole is divided into two parts by a slot.
As one portion of the pole is shaded by copper ring there will be induced current in the shade ring which will produce another flux φ2‘ in the shaded pole. So, resultant flux of shaded pole will be vector sum of φ1 and φ2. Say it is φ2, and angle between φ1 and φ2 is θ. These two fluxes will produce a resultant torque,
There are mainly three types of shape of rotating disc are available for induction disc type relay. They are spiral shaped, round and vase shaped, as shown. The spiral shape is done to compensate against varying restraining torque of the control spring which winds up as the disc rotates to close its contacts. For most designs, the disc may rotate by as much as 280o. Further, the moving contact on the disc shift is so positioned that it meets the stationary contacts on the relay frame when the largest radius section of the disc is under the electromagnet. This is done to ensure satisfactory contact pressure in induction disc type relay.
Where high speed operation is required, such as in differential protection, the angular travel of the disc is considerably limited and hence circular or even vane
types may be used in induction disc type electromagnetic relay.
Some time it is required that operation of an induction disc type relay should be done after successful operation of another relay. Such as inter locked over current relays are generally used for generator and bus bar protection. In that case, the shading band is replaced by a shading coil. Two ends of that shading coil are brought out across a normally open contact of other control device or relay. Whenever the latter is operated the normally open contact is closed and makes the shading coil short circuited. Only after that the over current relay disc starts rotating.
One can also change the time/current characteristics of an induction disc type relay, by deploying
