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How much current ?

Posted by eci22 
How much current ?
May 31, 2015 07:20AM
Hi I

I am building a CNC machine there are two components that require AC input- the spindle and the motor power supply, both take AC power and convert into DC
I want to provide the AC signal from a single IEC socket wired in parallel , it's rated for 10 amps, will powering the two components go over 10 amps and how do you calculate how much AC amps the two components will draw, this theory is beyond my current electrical knowledge at this point

Here is the spindle

Spindle


PSU
PSU


Spindle- 500watts 100volts means it will provide 5 amps DC at max load
PSU- 36volts 10 amps DC

I'm in the UK so both will receive 240volts AC. Will I trip a 10 amp AC Fuse ?
Re: How much current ?
May 31, 2015 07:43AM
Power out can't exceed power in.

The 36V 10A supply is good for 360W. Efficiency is probably on the order of 75% or so, so power input (from the power line) is about 500W

Your spindle power is about the same, so you're looking at about 1 kW power into the two devices. Power is roughly voltage x current, so at 240VAC, current will be 4-5A. Use a fuse that is rated a few amps higher. Your local electrical code may require specific margins/limits.

Switching power supplies typically require surge current when first turned on, so avoid fast-blow fuses unless you want to keep replacing the fuse.
Re: How much current ?
May 31, 2015 11:17AM
Ah that's a great explanation, thank you very much really appreciate it
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