Hi, I have the following question from an old City & Guilds paper:
A resistive load rated at 65 W, 110 V is to be used on a 230 V, 50 Hz supply.
Calculate
(a) current in the load
(b) voltage drop needed across a pure inductor connected in series with the load
(c) inductance of this inductor
(d) phase angle of the circuit
(e) explain the advantage of this type of current limitation and give one practical example.
Could someone point me to any reading material on this please as I can only find items relating to MCBs and fuses.
Many thanks.

 

Search for RL circuits - wiki for example.

 

Hi, I have the following question from an old City & Guilds paper:
A resistive load rated at 65 W, 110 V is to be used on a 230 V, 50 Hz supply.
Calculate
(a) current in the load
(b) voltage drop needed across a pure inductor connected in series with the load
(c) inductance of this inductor
(d) phase angle of the circuit
(e) explain the advantage of this type of current limitation and give one practical example.
Could someone point me to any reading material on this please as I can only find items relating to MCBs and fuses.
Many thanks.

The way you go about this depends highly on what you have studied before this.
Do you understand how to use complex numbers to analyze AC circuits? if so this is going to be fairly simple for you.
So you will have to state what kind of analysis you have done in the past or what you think you can use to solve this.

 

It might help to plot what you know about the problem on a phasor diagram. Note that these will be voltage phasors because the component currents are the same in a series circuit.

 

Search for RL circuits - wiki for example.

Thanks.

 

The way you go about this depends highly on what you have studied before this.
Do you understand how to use complex numbers to analyze AC circuits? if so this is going to be fairly simple for you.
So you will have to state what kind of analysis you have done in the past or what you think you can use to solve this.

Thanks. I will have to travel into the depths of my memory for complex numbers.

 

It might help to plot what you know about the problem on a phasor diagram. Note that these will be voltage phasors because the component currents are the same in a series circuit.

Thanks.