With the aid of a suitable diagram to aid your explanation, show that for a linear, non- saturated magnetic system comprising of a coil carrying some current I, the energy stored in the magnetic system, W, is
W 1 LI 2 2
Now draw a typical electromagnetic simple relay actuator arrangement, showing the soft iron, moving armature, position of the coil, airgap and return spring. Moreover, give an explanation as to how the relay functions.
A particular simple relay has a coil of N = 1200 turns, a cross sectional area of the soft iron, A = 100mm2, and airgap length X = 5mm when the armature is in the open position, and X = 2mm when the armature is in the closed position. If the spring which keeps the relay contacts open has a spring constant of 1Nm, show how the current to close the coil may be calculated, and give the current level. Furthermore, show the calculation which then gives the current at which the relay opens, stating the current level.
Explain why the current levels to close and open the contacts are not equal, and explain how this may be of benefit to the correct operation of the relay.
A transistor switch is used to energise the simple relay from a 48 V supply (Vs). The relay possesses a coil resistance of R = 30 Ω and an inductance of L = 0.06 H as shown electrically in Figure 1. The relay switches on for currents of 0.5 A or greater but does not switch off until the current has fallen below 0.2 A or less. The transistor is controlled by the drive voltage vB and you should assume that the transistor and the diode exhibits the ideal characteristics of instantaneous switching and zero on-state voltage drop. The transistor T is protected from the effects of energy stored in the relay inductance by the diode resistor network D-Rs.
Figure 1 – Relay driver
Delivering a high-quality product at a reasonable price is not enough anymore.
That’s why we have developed 5 beneficial guarantees that will make your experience with our service enjoyable, easy, and safe.
You have to be 100% sure of the quality of your product to give a money-back guarantee. This describes us perfectly. Make sure that this guarantee is totally transparent.Read more
Each paper is composed from scratch, according to your instructions. It is then checked by our plagiarism-detection software. There is no gap where plagiarism could squeeze in.Read more
Thanks to our free revisions, there is no way for you to be unsatisfied. We will work on your paper until you are completely happy with the result.Read more
Your email is safe, as we store it according to international data protection rules. Your bank details are secure, as we use only reliable payment systems.Read more
By sending us your money, you buy the service we provide. Check out our terms and conditions if you prefer business talks to be laid out in official language.Read more