ammeter question... DC and AC

[funkydiplomat]

Dudes. I was thinking about building a small box with a panelmount ammeter and AC mains connectors on it to monitor current draw on pesky amps that blow fuses. Or maybe to get the fuse size right on something i build from scratch.


I noticed that they list them as AC amp meters and DC amp meters. This means AC coupled and DC coupled, correct? Amps is amps, no? I should be able to use either for my application?

Is it common practice to bring up a troublesome amp slowly on a variac while monitoring total current draw? So you could shut it off before something crazy happens. Makes sense to me. what do ya'll do?

thanks in advance

joe

 

[jdbakker]

[quote author="funkydiplomat"]Dudes. I was thinking about building a small box with a panelmount ammeter and AC mains connectors on it to monitor current draw on pesky amps that blow fuses. Or maybe to get the fuse size right on something i build from scratch.[/quote]
http://www.thinkgeek.com/gadgets/electronic/7657/

JDB.
[Volts! Amps! Watts! Probably cheaper than DIY, too]

 

[bcarso]

Duke Aguiar loaned me one of his spare Valhalla Scientific digital power analyzers. They are pretty pricey, but having it is remarkably convenient. In particular you can see how much of the apparent current is really contributing to power, as it takes relative current-versus-voltage phase into account.

 

[CJ]

cheap and permanent solution, get a high perm torroid, put some turns on it, put your 120 feed line thru, feed the output to a junk VU meter and calibrate.

 

[Ptownkid]

JDB, I saw that guys on mythbusters the other night, glad someone mentioned it.

 

[jdbakker]

[quote author="bcarso"]Duke Aguiar loaned me one of his spare Valhalla Scientific digital power analyzers. They are pretty pricey, but having it is remarkably convenient. In particular you can see how much of the apparent current is really contributing to power, as it takes relative current-versus-voltage phase into account.[/quote]
As does that $30 Kill-A-Watt, by the way. It can display W, VA and power factor (which is directly related to the V-to-I phase difference).

JDB.
[not affiliated with either P3 International or ThinkGeek. Used a Kill-A-Watt when I was in the US; am very sad they have no 230V-compatible models]