Voltage Drop When Load Is Connected

It sounds like the transformer can't deliver the power the coil needs. I'd check the ratings on both the transformer and the load. The transformer output current/power rating should be higher than the load's input ratings. Both should have the same voltage rating.

24V / 8.6Ω ≈ 2.8A. 24V x 8.6A ≈ 206VA

Is a useful AC voltage still coming from the transformer when the circuit is switched on?

• If the transformer outlet volts (measuring AC) drop away when the circuit is switched on, then there is a fault in the transformer, or it is too small.

What happens when an ammeter is introduced to the circuit? Is there 2.8A in the circuit when the circuit is switched on?

• If not, and there is still voltage from the transformer when the circuit is switched on, then something has failed in the circuit between the inlet of the rectifier and the outlet terminal of the circuit such that it presents a high resistance, though not an open circuit. Measuring DC volts, chase the circuit through to find the failed component. There will be somewhere near 24V across it with the circuit switched on.

Transformer rating needs to be checked. (Should be 100Va atleast)

By the way..PWslack...VA is 24V X 2.8 A = 67.2 VA

just a sight slack.....

Interchanging the transformer would isolate the transformer issues.

Keep us posted....

You say the diode is OK - but is it the right way round? Just a thought ...

... I assume you were referring to the diode across the coil (?) ...

On the 24 V, take a 1000 Ohm, 1 w resistor (or roughly that size) and see if that makes the 24 V go to zero also.

The transformer is too small for the load. It sounds like the load is pulling too many amps to the amount VA supplied, therefor deminishing the voltage to the load. Does the transformer also supply the relay?

What is the distance between the power supply and the load, there could be feed line loss if the gauge of the wire was to small. This may be misleading because as the gauge increases the wire gets smaller in cross section but I think that you know what I mean.

but when we connect the clatch coil back and operated the voltage drops to zero.

I assume this means that the transformer is putting out the correct voltage without load.

How long before the voltage drops?

This transformer may have thermal overloads. The transformer maybe undersized or the thermal senors may have gone bad.

Check all your connections to make sure they are clean and tight, and if there are any solder connections, make sure they are sound. I once had the secondary winding lead connection on a stepdown transformer cut our butt for hours when it would deliver the correct voltage open circuited but under load would go to near zero. What we finally determined was that the output cable had momentarily shorted and when it did, it blew the connection off the transformer terminal board but it then touched back and made a pin point solder connection. It would pass rated voltage at no load but would drop it all at that point under load. It was found out when the heavy lift maintenance manager walked on the crane wondering why it was taking us so long to fix the crane (which was rented and supposed to be working the container ship it was boomed down over). He witnessed what was going on for a while, tried some of the same things we had done and was befuddled as us. He finally said he was going to find out what was going on and soldered two leads to each end of a fuse and connected it across the transformer output. Then the system was powered up and the fuse did not blow. He looked behind the terminal board on the transformer and showed us the melted-reconnected lead. We all looked at each other like we were a bunch of dumbasses, but this certainly was a new one for us all. We cut off the wire, resoldered the connection and everything then worked fine.

I assume that the system was working before this problem appeared...

You are obviously exceeding the power supply rating. However, if voltage just drop to zero, without any fuse popping or transformer cooking, (you never mentioned that they do...) it might have a current sensor as a protection measure. If so the problem might be right there, and the sensor is faulty or needs adjustments. if they do pop, than did you check the lifting motor for short or stuck gear? Try to by-pass the clutch-relay part and lift the gate and see what happen.

If nothing works, let us know again.

Wangito.

You are very correct. So many are trying to help . The one who asked the question is sitting tight and enjoying. not even bothering to at least give any feed back to the remarks and questions raised by so many.Probably he may not have visited the site again.He has not even told weather this is a problem which came later or is an original one so that people could at least under stands the reason for the problem to provide a solution . Are we wasting our time?

I love this,

Colesha just doesn't give a Sh$%.

Unfortunately, nothing we can do about it. Or, maybe we can? do you have an idea? Does anybody have an idea? How about a Sh$% list?....I am going to put it as a question for all to think about.

Wangito.

It's a tricky one. As long as we have an open forum, we have to expect it from Guests - I find I don't try too hard to sort out a Guest problem (unless it really grabs me anyway) - especially if they haven't come back within a day or two.

This one is when someone has registered - so you thing "Hey - genuine guy - let's sort out their problem, and maybe they can contribute something back". We have:

Colisha - from cna (?) -

• Join date: 4-Feb
• Total posts: 1
• Last post: 4-Feb, 2:30pm
• Last visit: 4-Feb, 3:00pm

Could be extenuating circumstances, so I don't see how we could introduce a list, or really any other measure against registered members. Don't half give me the hump, though!

Sorry guys i have been having a problem with ma pc and internet,all your suggestions are pretty cool,We had to change some of the wires that were faultydue to old age and had caused the problem especially in the lifting motor connection box had was soo dum due to moisture from an adjuscent ventilation pipe,

thanks alot and sorry.i appologise for that and please accept my appology.

it may be that your wires may be revers check the polarity and if power supply is to far from gate your wire size to small that is why nothing has blow

nick

qc.ca.

Check for any dry solder or loose contact if not straight away replace the rectifier, it happend some times that the diodes will show correct reading when cold check but will not supply enough current when under load.

1. Check AC output of transformer ONLOAD.

OK if nearly 20V,

Transformer may be culprit if voltage here is low, othereise <rectifier bridge> is suspected.

2. Have a filter capacitor after <rectifier bridge>?. If not even then it should work, but better to have one at least more than 1000 µF.

hi this is a normal phenomina while using an unregulated dc power supply and solution is use a regulated power supply of 24v. cool