Class 4 (4th Engineer) MET 📅 Sep 2022

Exam Question

(a) Describe the measures to be taken and the effect on various outputs when running a 60Hz system on a 50Hz supply. (6)

(b) A series circuit consists of a capacitor of 50µF and a coil of inductance 1.5H and resistance 300 Ohms. Find the total impedance when working on a 50Hz Supply. Find whether the current leads or lags the voltage. (10)

Reference Answer

### Part (a): Effects of Running a 60Hz System on a 50Hz Supply
Operating electrical equipment designed for a 60Hz supply on a 50Hz supply can lead to significant operational issues and potential damage. The effects on various components are as follows:
**1. AC Induction Motors:**
* **Speed Reduction:** The synchronous speed of an AC motor is directly proportional to the supply frequency ($$N_s = \frac{120f}{P}$$). Reducing the frequency from 60Hz to 50Hz will cause the motor to run approximately 16.7% slower.

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