pcb hole diameter

[trippj]

I'm looking for specification for pcb hole diameter to hand solder 18 ga. magnet wire that carries 300 volts 30 amp peak in our motor. Can you help with this?

Jim

 

[Foxfur]

I'd size the holes about .005 over the wire diameter. If that doesn't land you on a fractional or numbered drill size, just round up to the next highest bit. if the holes are plated through, you will need to take the plating thickness into account when specifying the size.
Foxfur

 

[melone]

Are you sure 18ga. is big enough? 300V @ 30A is alot of power (9000W)!

 

[Lewish]

Mil-spec 275 calls for the finished hole diameter to be 0.008 to 0.013 inches larger than the cross-section of the lead soldered into the hole. In a typical plated thru hole, expect the finished hole to be 0.002 to 0.004 inches smaller than the drill size. My 1976 copy of the spec calls for a plated thru hole diameter of 0.063 inches for 18 ga wire.
It also states that the maximum allowable nominal current for 18 ga is 7 amps and that the wire will fuse at 83 amps. I think you should consider this in your design.

 

[jbartos]

Suggestion: Size the conductor for ampacity = 1.25 x full load motor current (FLA), if you have FLA available. Usually, it is in the motor specifications and on the motor nameplate.

 

[hestec]

I have the same question that "melone" has, that's lot of wattage and amperage for a 18 gauge wire? Also, what kind of traces are you putting on the PCB to carry the current?

 

[automatic2]

You maybe should consider making this a mechanical connection.

 

[nbucska]

Melone:
Only the current and wire R have to be taken into consideration, V is irrelevant. <nbucska@pcperipherals.com>

 

[melone]

True, but if you are trying to supply power to a 9kW motor, I don't think 18ga is the wire that should be used!