Discussion in 'General Electronics Chat' started by repairs online, Apr 2, 2012.

1. ### repairs online Thread Starter New Member

Nov 3, 2007
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I am interested in quick practical suggestions, easily accessible components to make up a dummy load for a 24V / 10Amp power supply.

2. ### strantor AAC Fanatic!

Oct 3, 2010
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Stovetop elements. this website say that "a large cooktop surface burner is usually in the area of 27 ohms, a small 45 ohms" which gives you 8.4375ohms in parallel. you need 2.4ohms to test 10A. 4 sets all in parallel would be an 11.4A dummy load. check craigslist, people are always putting ovens out by the curb

3. ### K7GUH Member

Jan 28, 2011
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I favor 12 volt 50 watt bulbs in series / parallel to come up with the desired load. That's if you can't find abandoned electric cooktop burners.

4. ### repairs online Thread Starter New Member

Nov 3, 2007
38
0
While the mathematics check out pretty close where would one find 12V 50W lamps or even worse stove elements.

I mean something more practical. Using bulbs has the disadvantage of current, more current flowing at switch on, which may affect the power supply.

To the power supply in mind a CL-A1-250-24, how about schematics. This power supply trips the line fuse with no load connected.

A CL-A1-250-24 has input of 220Vac (can tolerate 240Vac) and DC output of 24V 10A. It is a switching power supply.

Last edited: Apr 2, 2012
5. ### #12 Expert

Nov 30, 2010
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Cars! Cars use 12 volt light bulbs. Go to a junque yard and get a couple of headlights and your pockets full of smaller light bulbs. Start the power supply into one bulb and keep adding until you get to 10 amps.

6. ### strantor AAC Fanatic!

Oct 3, 2010
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So what do you think it's going to do when you load the output to 10A?

What size is your fuse? Have you tried using a time delay fuse to allow for high inrush current? Power supplies have big hungry capacitor banks inside.

7. ### studiot AAC Fanatic!

Nov 9, 2007
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These can be had at sensible cost, including voltage and current monitoring. they are used to test batteries, alternators, cutouts, regulators etc.

8. ### repairs online Thread Starter New Member

Nov 3, 2007
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The power supply has an inrush current limiter NTC, MF72 5d15, thermistor. Two reservoir caps, each 470μF @ 200V. All three components check out ok.

Connected to the input of the power supply which is 240Vac have other wires connected in parallel feeding other circuits. These feeds have been disconnected thus leaving only the power supply. Whether, the output of the power supply, 24Vdc, is connected or disconnected to the circuit which it provides power, the line fuse still tips.

One of the tests carried out, at the beginning was the mains power filter which is housed in a box. However, this test was done only with the wires open, in which case, the line fuse did not trip.

I should have connected a 100W lamp to check it under load whether it would trip the line fuse or not.

Otherwise, the tripping of the line fuse lies within the power supply.

This power supply uses 2 x 2sc2625, a D92-02 (cathode to cathode connected) and a KA7500B control ic.

The switching transformer is a CLZ200F21-GC2, but I can not find its internal connections on the net.

Have also checked a number of other components, but they seem to be ok.

Last edited: Apr 3, 2012
9. ### strantor AAC Fanatic!

Oct 3, 2010
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is there a switch or jumper on the power supply to select between 120V/240v?

10. ### repairs online Thread Starter New Member

Nov 3, 2007
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No, no switch. The power supply is designed for 240Vac operation. As for the jumber, I did not really look.

It would be nice to have the schematics.