Questions and answers

What is relay torque?

What is relay torque?

The universal torque equation explains the working of an electrical relay. The relay has some arrangement of electromagnetic. These electromagnetic consist current and voltage windings. And the torque is produced by the interaction of the flux of the same winding or between the flux of both the windings.

How is the braking torque provided in an induction relay?

A permanent magnet of high retentivity steel is provided to give eddy current braking to the disc. This is necessary to reduce to a minimum the over-run of the disc in case the current or voltage providing the driving torque stops before the operation has been completed.

What is the induction relay?

An induction relay essentially consists of a pivoted aluminium disc placed in two alternating magnetic fields of the same frequency but displaced in time and space. The torque is produced in the disc by the interaction of one of the magnetic fields with the currents induced in the disc by the other.

What is the purpose of drag magnet in induction relay?

Time delay is obtained in induction-type relays by a “drag magnet,” which is a permanent magnet arranged so that the relay rotor cuts the flux between the poles of the magnet, as shown in Fig. 4. This produces a retarding effect on motion of the rotor in either direction.

What is a seal in relay?

The Seal-in relay is energized by the Sudden Pressure Relay micro switch; its purpose is to close alarm and/or trip circuits and seal itself closed until manually reset by the reset pushbutton.

Where is induction relay used?

Induction-type relays are the most widely used for protective-relaying purposes involving AC quantities. They are not usable with DC quantities, because of their principle of operation. An Induction Type Relay is a split-phase induction motor with contacts.

What measures Siemens?

Siemens (S), unit of electrical conductance. In the case of direct current (DC), the conductance in siemens is the reciprocal of the resistance in ohms (S = amperes per volts); in the case of alternating current (AC), it is the reciprocal of the impedance in ohms.

What is RX diagram?

The R-X graph shows an apparent impedance which has a complex relationship to the actual Rf depending on the power system conditions. The fault position vs. true Rf graph can remove all of those effects and show the true performance no matter what the power system conditions are.

How is torque developed in an induction relay?

Electromagnetic-induction relays use the principle of the induction motor whereby torque is developed by induction in a rotor; this operating principle applies only to relays actuated by alternating current, and in dealing with those relays we shall call them simply “induction-type” relays.

What is the Universal torque equation for a relay?

The universal torque equation explains the working of an electrical relay . The relay has some arrangement of electromagnetic. These electromagnetic consist current and voltage windings. The current through the winding produces magnetic flux.

How are magnetic fields induced in an induction relay?

The two rings have currents induced in them by the alternating flux of the electromagnet and the magnetic fields developed by these induced currents cause the flux, in the portions of the iron surrounded by the rings to lag in phase by 40° to 50° behind the flux in the un-shaded portions of the pole. The driving torque is given as –

What’s the difference between induction Cup Relay and induction motor?

Compared to induction motor the difference is that in induction cup relay the rotor core is stationary and only rotor conductor portion is free to rotate about its axis. The currents and respective fluxes produced by the two pairs of coils are displaced from each other by angle ∝.