Hi all,
In my LM4702 amplifier I am using a Finder 4052 series double contact relay for switching the 500VA mains transformer. The relay connected on both live and neutral line.
Anyway, my problem is, a really big spark appears between relays contacts while swtiching on and off. It also makes a big noise like (I dont know like what, but a big noise really frightening)
Does anyone know a solution for this?
Thanks in advance..
In my LM4702 amplifier I am using a Finder 4052 series double contact relay for switching the 500VA mains transformer. The relay connected on both live and neutral line.
Anyway, my problem is, a really big spark appears between relays contacts while swtiching on and off. It also makes a big noise like (I dont know like what, but a big noise really frightening)
Does anyone know a solution for this?
Thanks in advance..
The relay contacts are like a pair of capacitor plates -- as they come together the capacitance increases -- so much so that the charge arcs over.
The solution is a QuenchArc -- you can buy or make -- basically a film capacitor with a resistor in series -- this dissipates the charge while the contact are moving into proximity.
The solution is a QuenchArc -- you can buy or make -- basically a film capacitor with a resistor in series -- this dissipates the charge while the contact are moving into proximity.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Hi,
the relay should not be connected to Live AND Neutral.
A double pole isolation switch is normally used for mains isolation.
The switch contacts should normally have a large gap to ensure safe isolation.
A relay cannot usually meet this contact gap requirement. It can do on/off duty but not isolation.
The relay is usually fitted to the Live line only to do on/off duty.
If you have fitted a soft start circuit, then the time delayed relay is across the current limiting device. Again this is usually fitted to the Live line.
the relay should not be connected to Live AND Neutral.
A double pole isolation switch is normally used for mains isolation.
The switch contacts should normally have a large gap to ensure safe isolation.
A relay cannot usually meet this contact gap requirement. It can do on/off duty but not isolation.
The relay is usually fitted to the Live line only to do on/off duty.
If you have fitted a soft start circuit, then the time delayed relay is across the current limiting device. Again this is usually fitted to the Live line.
Hi,jackinnj said:
the spark quencher usually works when the switch is breaking. The visible spark is due to the inductance in the load trying to continue drawing current when the switch opens. The faster the switch opens the higher the voltage that the load inductance creates in an attempt to jump across the opening gap. That is also part of the reason for the wide contact gap mentioned in the earlier post.
It is quite unusual to have a significant spark at switch on. Yes the air insulation in the rapidly closing gap can break down and allow the current to start flowing before the gap actually closes, but the time delay between initiation of this closing spark and the contact actually touching is tiny. In addition the current will tend to be delayed by the action of voltage/inductance/phase relationship and so little current will be allowed to flow in the instant of establishing the near zero resistance across the closing switch.
I was recalling from a apnote written by Mallory. You're most likely correct.AndrewT said:
It is interesting to noodle around this issue -- in CNC machining the small burst of energy caused one company to have holes go slightly out of round (or more acurately, perfect concentricity) as the power was switched off and the router bit removed.
But the point is;
the switch should not be sparking when you close. You said it did. Is it wired in correctly?
A switch does spark when breaking a circuit, but when enclosed as mains switches are, the spark is not normally visible. Have you wired it in correctly?
Go back and check what you have done.
the switch should not be sparking when you close. You said it did. Is it wired in correctly?
A switch does spark when breaking a circuit, but when enclosed as mains switches are, the spark is not normally visible. Have you wired it in correctly?
Go back and check what you have done.
Ok I will post some photos in one hour.
In fact I have removed the relay on mains input because of that situation. Now I am using is as mute switch.
But I will put the old position it and will shot some pics.
By the way, I bought a Ultrasone DJ-1 headphone today and now I am listening it with my ipod... Its a good headphone! I strongly recommend it! It makes real difference!
Thx.
In fact I have removed the relay on mains input because of that situation. Now I am using is as mute switch.
But I will put the old position it and will shot some pics.
By the way, I bought a Ultrasone DJ-1 headphone today and now I am listening it with my ipod... Its a good headphone! I strongly recommend it! It makes real difference!
Thx.
An externally hosted image should be here but it was not working when we last tested it.
Thats the connection. The blue line is live.
Hi,
does the blue connect COM to mains fuse??
Does the black connect NO (normally open) to transformer primary??
Are the other 4 connections are left empty??
The NC should not spark, it is unconnected.
The other half of the double pole should not spark, it is unconnected.
I see a 24V ~ next to the coil symbol.
Are the contacts rated for mains use?
Please confirm all these.
You could swap the blue and black so that mains comes into NO and exits via COM to the transformer. Your existing arrangement leaves both COM and NC live when the relay is off.
You could run Neutral to term24 and connect term21 to the other transformer primary.
Before you test this again, plug it in via a mains light bulb.
does the blue connect COM to mains fuse??
Does the black connect NO (normally open) to transformer primary??
Are the other 4 connections are left empty??
The NC should not spark, it is unconnected.
The other half of the double pole should not spark, it is unconnected.
I see a 24V ~ next to the coil symbol.
Are the contacts rated for mains use?
Please confirm all these.
You could swap the blue and black so that mains comes into NO and exits via COM to the transformer. Your existing arrangement leaves both COM and NC live when the relay is off.
You could run Neutral to term24 and connect term21 to the other transformer primary.
Before you test this again, plug it in via a mains light bulb.
The blue cable is from mains filter and before it there is a 5A fast fuse. (Before it was 3A and always blowing)
Anyway,
The blue cable is connected to COM clamp. And from NO clamp I get the transformers one of the primary inputz. The other primary is connected directly to the mains filters other pin.
The all other pins are blank as you can see..
I hope that all clear.
Concerning the relays signs. The relays coil is 24v AC rated so I can control it from my preamps transformer. And the contact ratings for this relay is 8A (250V) AC for both two contacts. Then If I connect them in parallelled, I can have a 16A contact. In fact I guess only one contact will be enough for me.
Anyway,
The blue cable is connected to COM clamp. And from NO clamp I get the transformers one of the primary inputz. The other primary is connected directly to the mains filters other pin.
The all other pins are blank as you can see..
I hope that all clear.
Concerning the relays signs. The relays coil is 24v AC rated so I can control it from my preamps transformer. And the contact ratings for this relay is 8A (250V) AC for both two contacts. Then If I connect them in parallelled, I can have a 16A contact. In fact I guess only one contact will be enough for me.
It sounds like you have the correct connections.
I still cannot understand sparking when closing the NO switch.
I can see that the orange translucent cover would allow a spark to be visible when opening the NO switch.
Your fuse problem is two fold;
1.) use a T rated fuse for powering transformers and motors and other inductive loads.
2.) use a soft start to reduce the start-up current of your toroid transformer.
Without a soft start the fuse should allow about 3times the power rating into the transformer. 500VA on 220/240 Vac requires T6A fuse.
With soft start the fuse rating can be as low as 0.5times the power rating of the transformer. 500VA on 220/240 can run between T1.25A to T2.5A fusing.
I still cannot understand sparking when closing the NO switch.
I can see that the orange translucent cover would allow a spark to be visible when opening the NO switch.
Your fuse problem is two fold;
1.) use a T rated fuse for powering transformers and motors and other inductive loads.
2.) use a soft start to reduce the start-up current of your toroid transformer.
Without a soft start the fuse should allow about 3times the power rating into the transformer. 500VA on 220/240 Vac requires T6A fuse.
With soft start the fuse rating can be as low as 0.5times the power rating of the transformer. 500VA on 220/240 can run between T1.25A to T2.5A fusing.
OK.
But there is a misunderstanding I guess.
The spark appears while powering on! Means while contact is getting close position, not while opening. In fact I cannot see any reason to spark appearing while contacts leaving! Why?
The start-up current is available only while powering up. So why it should happens while powering off.
But there is a misunderstanding I guess.
The spark appears while powering on! Means while contact is getting close position, not while opening. In fact I cannot see any reason to spark appearing while contacts leaving! Why?
The start-up current is available only while powering up. So why it should happens while powering off.
I thought that it will jump!
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