This is topic Carbon arc volts/amps in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.
To visit this topic, use this URL:
https://ft-forum.com/ft/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=1;t=002100
Posted by Paul Cunningham (Member # 501) on 03-31-2001, 07:35 AM:
I am mucking around with a couple of Peerless magnarcs at the moment. Not having a multimeter I got a friend to come around with his clamp meter and see exactly what current I was drawing, the results confuse me, this is what I have;
7mm negative
8mm positive
250v 50Hz running into a transformer then a basic rectifier
Output current when running is 55 amps at 3 volts.
The 3 volts is what confuses me as I was expecting around 30-40 volts.What do you think?
Thanks Paul
Posted by Jerry Chase (Member # 660) on 03-31-2001, 08:35 AM:
Check the meter setting? See if it registers a battery properly. My guess is the meter is being read at 1/10th value.
Posted by Rick Long (Member # 213) on 03-31-2001, 01:06 PM:
If memory serves, typical ratings for this trim should be around 70 amps at 25 - 30 VDC.
You did remember to dial the meter to D.C. volts, right?
Posted by John Walsh (Member # 168) on 03-31-2001, 01:26 PM:
I find that clamp on ampmeters for DC fairly inaccurate.3 volts is not right, especially if the lamp is working normally. If so, I'd suspect the meter.
Posted by Paul G. Thompson (Member # 655) on 03-31-2001, 04:05 PM:
I think your voltmeter has gone goofy.Or, two other things:
If you are measuring the voltage using ground as a reference and you have only three volts, the lamphouse might be "floating".
If you are measuring using the negative lead as a reference, you should read the correct voltage. If not, your voltmeter is definately HS.
Posted by Gordon McLeod (Member # 33) on 03-31-2001, 04:32 PM:
70amps at 42 volts is the rateing on the 7mm negwith a 8mm positive
Posted by Paul Cunningham (Member # 501) on 04-01-2001, 09:52 AM:
Thanks everyone,
The arc is burning fine.
I thought as Jerry did that it was only reading 1/10th value but it didn't indicate that was the case.
I will try it with another meter and see what I get.
Paul
Posted by Michael Barry (Member # 237) on 04-02-2001, 12:12 PM:
Paul: I would LOVE to see a carbon arc lamphouse in operation - never seen one working before! (On the screen, yes - in the booth, no.)If I ever get around to going to Melbourne I'd love to have a look...
Posted by John Pytlak (Member # 331) on 04-02-2001, 12:21 PM:
Film-Tech has the 86-page National Projector Carbon Bulletins in the "Miscellaneous" listing of the "Manuals" section. The bulletins have a wealth of information on carbon arc lamps, with excellent background information on light measurement and optics.------------------
John P. Pytlak, Senior Technical Specialist
Worldwide Technical Services, Entertainment Imaging
Eastman Kodak Company
Research Labs, Building 69, Room 7419
Rochester, New York, 14650-1922 USA
Tel: 716-477-5325 Cell: 716-781-4036 Fax: 716-722-7243
E-Mail: john.pytlak@kodak.com
Web site: http://www.kodak.com/go/motion
Posted by Paul Cunningham (Member # 501) on 04-02-2001, 08:43 PM:
MichaelYes, feel free to call in whenever you get a chance to come down, tha lamps are in my garage at the moment!
John, I have downloaded the National Carbon bulletins.
Paul
Posted by Stefan Scholz (Member # 147) on 04-05-2001, 12:08 PM:
Mycarbon lamp ran around 40 Volts with 7/8 MM.