Electrical questions, voltage and surge protection for router and lathe

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Forum topic by denali posted 08-29-2014 06:50 PM 1966 views 0 times favorited 2 replies Add to Favorites Watch
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1 post in 2729 days

08-29-2014 06:50 PM

Topic tags/keywords: question lathe router electrical voltage surge protection

Hi everyone,

Been looking at LumberJocks for a few months now, just now finally got around to joining, this is my first post. I’m US-to-Argentina transplant, been living in Patagonia 12 years now. Last year while visiting my folks in the US, I finally bit the bullet and upgraded my router table and lathe. Bought a Nova DVR XP and a Porter Cable 7518/ Incra lift, neither of which I could find down here (nor anything remotely similar). Transport and customs were a beast, but the jump in quality is worth it.

2 questions:

1. Surge protection for lathe.

The DVR lathe has no problem switching voltage/frequency, but specifies that it needs a surge protector. However, that protector needs to be able to handle the high current the motor draws. Around here, what’s available is either a dinky thing designed for a computer, that won’t handle the draw, or a breaker-style voltage protector that will cut off if voltage goes above 252 or below 168. That seems to me to stray quite far from the 220 I ought to be getting. The DVR has delicate electronics, can they handle a voltage swing that large? I wrote to Teknatool a couple of weeks ago, no response. Might be because they aren’t licensed to deal in Argentina, or because they don’t read their email. Any thoughts appreciated, I’m anxious to get the thing started up, but given how much money and headache it took to get it down here, I don’t want to plug it in before I have it fully protected. Burning out that computer would be a killer.

2. Current drawn by PC7518

Since the router motor I got runs on 110, I have to run it with a step down 220-110 transformer. How much does it need to be rated to? The PC7518 is listed as a 15 amp motor, but the folks I went to buy a transformer from said to check what its maximum startup current draw is. If it runs 15 amps at 110, a 2000W transformer should be enough (110Vx15A=1650W). But they said if it draws lots of extra current on startup, I could burn out either the motor or the transformer in short order (might work a few times and then burn out.) Can’t find anywhere in the Porter Cable literature where it says anything about this, it’s always just listed as a 15 Amp motor. Any knowledge about this? If 15 amps is the max, then a 2000W transformer is fine, if more is necessary I’ll get it, but the jump to a 4000W version is considerably more expensive, and I’d rather avoid it if necessary.

Thanks so much! Once I get these 2 babies up and running, I’ll post them as finished projects, since I built a new router table and lathe stand from scratch for them. Keep up the good work and thanks for the help.


-- denali, from high in the patagonian andes

2 replies so far

View mpsprunger's profile


40 posts in 3197 days

#1 posted 09-05-2014 05:50 PM

amps x votls / 1000 will give you the KVA of the transformer. 1650 of course translats to 1.650 KVA so a 2 KVA transformer should work, even a 3KVA. but cost becomes a factor.

View ChrisK's profile


2061 posts in 4417 days

#2 posted 09-05-2014 07:17 PM

The surge protector does not need to handle the motor current. The surge protector is designed to prevent he voltage at the motor from spiking above a certain level. The clamping of the voltage by the surge protector is limited by the joule rating of the device. The higher the joule rating the more surge current from the voltage spike the device can absorb. Look for a 400V or less clamping voltage on the surge device.

For the start up current on the motor the transformer needs to be large enough to not allow the secondary voltage, the 115V, to dip. Not every 2KVA transformer may have enough copper and steel to prevent the drop in voltage due to the start up current. The lower the temperature rise for a given kva the better the transformer. Dig around a few transformer manufacturers sites for more info. Square D, Eaton, ABB and Siemens are a few of the big ones. They all make surge protectors as well.

-- Chris K

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