primary current calculation

[trebor]

First question from the 2391-20 this week

18 x 24 volt soldering irons to be supplied by a transformer via elv sockets, what is the design current of the primary circuit

i said the secondary load was 360va so choose a 400va transformer
the primary would be 400/230 = 1.73A, am I wrong or really wrong

 

[telectrix]

can't see how you can calcx. the va as you are only given the voltage of the irons, not the wattage.

 

[Deleted member 26818]

I get 1.2W for the soldering irons?

 

[telectrix]

can't be. wouldn't get even warm at 1.2watt. the q. just says 18 24v soldering irons. no mention of wattage or amperage.

 

[i=p/u]

assuming 230v supply then....

 

[trebor]

sorry I cant even get the question right let alone the answer , it should have been 20 x 18watt 24v soldering irons

 

[Sparky Ninja]

sorry I cant even get the question right let alone the answer , it should have been 20 x 18watt 24v soldering irons

that makes more sense

 

[keniff]

16 amp? Being they equate to 15? Not sure though

 

[i=p/u]

I=p/u 1.3a x 20= 26atransformer???????????????????????

 

[topquark]

I'll add you should assume that it's a 230V primary circuit.

 

[pmanku]

Thats 15A on the secondary so the primary current will be

15A x secondary voltage/primary voltage = 15 x 24/230 = 15 x 0.1 = 1.5A

 

[topquark]

Thats 15A on the secondary so the primary current will be

15A x secondary voltage/primary voltage = 15 x 24/230 = 15 x 0.1 = 1.5A

So the total design current for the primary circuit will be?

 

[pmanku]

The design current would be 1.5A.

 

[topquark]

The design current would be 1.5A.

For 18 soldering irons with that spec ????

 

[trebor]

yes it is fed from a 230V supply