2382-622 exam question

[IvayloP]

Hi there. I am a student part time for level 1 &2 in UK. I will have an exam 2382-622 but I stuck to one of the questions. Actually when I looked for information around and make some thinking about it I think the answer would be,B - Maximum demand, because everything else can be directly measured or calculated. Am I right with that though.
I don’t know why the picture can’t be attached. The answers are
A- nominal voltage
B- maximum demand
C- prospective fault current
D- earth fault loop impedance

 

[westward10]

Seeing the question might help.

 

[IvayloP]

Hi there. I am a student part time for level 1 &2 in UK. I will have an exam 2382-622 but I stuck to one of the questions. Actually when I looked for information around and make some thinking about it I think the answer would be,B - Maximum demand, because everything else can be directly measured or calculated. Am I right with that though.

Seeing the question might help.

Yes I agree Just edited it. There was some problem with the picture.

 

[westward10]

Which one of those is a characteristic which can be obtained by enquiry?
I have repeated the question because you need to rule out the three which are not found by enquiry.

 

[mainline]

Hi there. I am a student part time for level 1 &2 in UK. I will have an exam 2382-622 but I stuck to one of the questions. Actually when I looked for information around and make some thinking about it I think the answer would be,B - Maximum demand, because everything else can be directly measured or calculated. Am I right with that though.
I don’t know why the picture can’t be attached. The answers are
A- nominal voltage
B- maximum demand
C- prospective fault current
D- earth fault loop impedance

How would you determine the nominal voltage.

 

[IvayloP]

How would you determine the nominal voltage.

With direct measurements?

 

[IvayloP]

Which one of those is a characteristic which can be obtained by enquiry?
I have repeated the question because you need to rule out the three which are not found by enquiry.

Ehmm the nominal voltage can be measured as well as prospective fault current and earth fault impedance. Let to clarify my view. I am on site and have to connect new house for example. There is the main intake power cable and I can to measure what voltage is present also PFC and earth fault impedance. The thing that I don’t know is how much power the grid company is allowed to be used from it. But in other point of view, the regular electrician like me shouldn’t do that and I will find the main disconnector before the meter and probably two pole switch after it. From the value of the fuse before the meter I will know the maximum demand. Or maybe I missed something

 

[mainline]

Ehmm the nominal voltage can be measured as well as prospective fault current and earth fault impedance. Let to clarify my view. I am on site and have to connect new house for example. There is the main intake power cable and I can to measure what voltage is present also PFC and earth fault impedance. The thing that I don’t know is how much power the grid company is allowed to be used from it. But in other point of view, the regular electrician like me shouldn’t do that and I will find the main disconnector before the meter and probably two pole switch after it. From the value of the fuse before the meter I will know the maximum demand. Or maybe I missed something

Look at 313.1

 

[Tom256]

Ehmm the nominal voltage can be measured as well as prospective fault current and earth fault impedance... Or maybe I missed something

Do you understand the meaning of the word 'nominal'?

 

[IvayloP]

Do you understand the meaning of the word 'nominal'?

What you mean? The nominal voltage on the public supply is 230 for one phase and 400 for three phases. What you understand under public supply? Or you told me that the nominal voltage is the thing that only energy company can give me?

 

[IvayloP]

Look at 313.1

Thanks I will see it later, the book isn’t with me now. The tutor said all information is there but something is still missing to me.

 

[Tom256]

What you mean? The nominal voltage on the public supply is 230 for one phase and 400 for three phases. What you understand under public supply? Or you told me that the nominal voltage is the thing that only energy company can give me?

If you did not know the nominal voltage of the UK, could you take a voltage measurement at the new home in your example and know what it was?

 

[IvayloP]

If you did not know the nominal voltage of the UK, could you take a voltage measurement at the new home in your example and know what it was?

Yes of course. Actually it can be achieved only with seeing the type of the cable but this is less likely to be asked into that exam . Do you think the answer is the nominal voltage?
Wait!! I think I’ve got your point . I can do a direct measurement and will find some voltage there, but I will not know that this is the nominal voltage. The nominal voltage is kind of knowledge or if someone tells you what value it should be. Same as the nominal voltage of appliances you can’t measure it , you only can check the label or ask the manufacturer. Is that true?

 

[Tom256]

Yes of course. Actually it can be achieved only with seeing the type of the cable but this is less likely to be asked into that exam . Do you think the answer is the nominal voltage?
Wait!! I think I’ve got your point . I can do a direct measurement and will find some voltage there, but I will not know that this is the nominal voltage. The nominal voltage is kind of knowledge or if someone tells you what value it should be. Same as the nominal voltage of appliances you can’t measure it , you only can check the label or ask the manufacturer. Is that true?

The question relates to the * supply characteristics * this is the first key phrase. The first consideration is, from the available answers offered, which are characteristics of the supply. That is being tested first, can you identify what are characteristics of the supply.
The maximum demand of the installation is a very important first step aspect of determining the supply intake availability to be provided yet it, in itself, is a characterisitc of the load.

Of the three remaining options if an enquiry is made to the DNO they will provide values for each. However, for the external earth loop and the prospective fault current 'rule of thumb' values from Engineering Recommendations P23 and P25 will be provided to you. (side question: Do you know what they might be?).

The second key phrase therefore is 'NOMINAL voltage'.
The nominal voltage as you say is at a fixed value of 230 volts on a single phase supply, this is stated within the ESQCR, yet it is permitted to be within tolerances of +10% to -6% of that value at the supply intake position. If you take a measurement of the voltage at the intake of the property you could therefore read from 216 volts up to 253 volts.
If you did not know what the nominal voltage was set at then a measurement at the premises would not give you this defined value due to the permitted tolerances.

At least that is the way I am reading the question. Could have it totally wrong but at least I have done as was once always required at school and "show your working out boy".

 

[IvayloP]

The question relates to the * supply characteristics * this is the first key phrase. The first consideration is, from the available answers offered, which are characteristics of the supply. That is being tested first, can you identify what are characteristics of the supply.
The maximum demand of the installation is a very important first step aspect of determining the supply intake availability to be provided yet it, in itself, is a characterisitc of the load.

Of the three remaining options if an enquiry is made to the DNO they will provide values for each. However, for the external earth loop and the prospective fault current 'rule of thumb' values from Engineering Recommendations P23 and P25 will be provided to you. (side question: Do you know what they might be?).

The second key phrase therefore is 'NOMINAL voltage'.
The nominal voltage as you say is at a fixed value of 230 volts on a single phase supply, this is stated within the ESQCR, yet it is permitted to be within tolerances of +10% to -6% of that value at the supply intake position. If you take a measurement of the voltage at the intake of the property you could therefore read from 216 volts up to 253 volts.
If you did not know what the nominal voltage was set at then a measurement at the premises would not give you this defined value due to the permitted tolerances.

At least that is the way I am reading the question. Could have it totally wrong but at least I have done as was once always required at school and "show your working out boy".

Yeah maybe I have a different view about something. In my country when the electrician should make a new DB he must now the maximum demand of the supply , what that main cable and power company can provide. This usually is the amount of the MCB after the meter , the power batch - 10kW, 15kW e t c. Only after that he can do thinking about how the DB will be made and what circuits should include to fit in that. And then the maximum demand of the load comes to each circuit. Maybe this is wrong interpretation because of the two different languages and because of that, that I have knowledge from other country make me to think different on such questions. But thank you about your help. Tomorrow will be my exam, I hope it will be successful. Have a great day