Help please. "Kettle" lead fuse advice

[karlfer]

Please advise.

Just gota splendid Streamliner 600.
The provider from this parish has been extra decent and provided 2 kettle leads (yes I know people HATE that word ).

Both leads have 10 Amp fuses.

I'm sure the one that was on my Streamliner 900 was a 3 Amp fuse.

Definitive advice from expert would be most excellent .

I've spent the last half hour with Google being not much use

Cheers in advance oh wondrous Basschat Massive!

[4stringslow]

Strictly speaking, kettle lead fuses are there to protect the lead not the device they are plugged into. Indeed, USA and European versions don't even have a fuse. Thus, it is the responsibility of the amp, or whatever, manufacturer to include the appropriate fuse in their product because they should assume that the kettle lead itself is unfused.

So, for most** UK kettle leads it's ok to use a 13A fuse. This also means there's no need to worry about pairing a specific lead to a specific device.

There's no harm in using a lower rated fuse if you wish but there's really no need and you risk eventually getting leads mixed up and blowing a low-rated fuse if the lead is used in a high power device.


** this assumes the cable itself is rated for 13A. If the lead has been made with a lower rated cable then the fuse should be adjusted accordingly, but the principle remains the same - the fuse is to protect the lead, not the appliance.

Edited July 29, 2016 by 4stringslow

[Dad3353]

Notwithstanding the above, which is correct, you'd be better off with a 3 A fuse in my opinion.

[Happy Jack]

But if the fuse blows, try wrapping some silver foil around it.

[obbm]

Assuming that the cable is of adequate rating, the lowest rated item in the lead is the IEC connector.

Most IEC connectors are rated at 10A so a 10A fuse is perfect.

[karlfer]

Many thanks gents, the help is very much appreciated.

I guess I'll be fine as long as I wear rubber gumboots .

Thanks again,
Karl.

[gary mac]

[quote name='karlfer' timestamp='1469805366' post='3101225']
Many thanks gents, the help is very much appreciated.

I guess I'll be fine as long as I wear rubber gumboots .

Thanks again,
Karl.
[/quote]s

You Northern chaps have some strange stage wear.

[karlfer]

[quote name='gary mac' timestamp='1469805581' post='3101227']
s

You Northern chaps have some strange stage wear.
[/quote]

Gi ower lad, tens neetweer

[gary mac]

[quote name='karlfer' timestamp='1469805716' post='3101229']
Gi ower lad, tens neetweer
[/quote]

[4stringslow]

[quote name='obbm' timestamp='1469805059' post='3101221']
Assuming that the cable is of adequate rating, the lowest rated item in the lead is the IEC connector.

Most IEC connectors are rated at 10A so a 10A fuse is perfect.
[/quote]

True, but ratings are, of course, deliberately conservative and 10A fuses are not commonplace in the UK. 13A fuses in a short IEC mains lead are acceptable according to IET codes of practice and BS1363.

[i]"Where manufacturer’s flex is less than 2m in length, has a csa of 0.75mm2 and is fitted with a non-rewirable plug, it may be rated at 10A and be fused to 13A, in accordance with BS1363 Table 2 note C." IET Code of Practice.[/i]
http://www.pat-testing-training.net/articles/fuse-ratings.php

Anyone using lower rated fuses and keeping all their IEC leads in one large box to be pulled out as needed would be wise to carry plenty of spare fuses

[MoonBassAlpha]

A 3A fuse is not right for an amp that could draw over 900W.
240V * 3A =730W. I'd go for a 10A fuse as stated above.
What is the rating of the internal fuse? My shuttle 6 has a T-5A internally and the max [i]average[/i] power is stated as 400W on the back of the amp.

[karlfer]

Don't know, can't actually find a fuse on the head

[Dad3353]

[quote name='karlfer' timestamp='1469820921' post='3101363']
Don't know, can't actually find a fuse on the head
[/quote]

Ah... So, Moriarty, you've not read the Manual [i]again[/i], eh..?

[url="http://www.genzbenz.com/img/manuals/gb/Streamliner_600_manual.pdf"]Streamliner 600 Manual ...[/url]

[quote]For countries using 220V, 230V, and 240V AC mains, select the 230V switch position on the Voltage Selector switch. [u]There is no externally accessible AC mains (line) fuse, the internal fuse is integral to the SMPS power supply and is not user serviceable[/u]. This fuse will not fail except under very unlikely fault conditions to the SMPS, and if this occurs a qualified service technician is required to correct the problem.[/quote]

[Norris]

A lower rated fuse may be mounted on the circuit board if it's not in an chassis mounted holder

Edit: Ah well there you go - Dad has the answer

Edited July 29, 2016 by Norris

[mcnach]

[quote name='MoonBassAlpha' timestamp='1469812063' post='3101293']
A 3A fuse is not right for an amp that could draw over 900W.
240V * 3A =730W. I'd go for a 10A fuse as stated above.
What is the rating of the internal fuse? My shuttle 6 has a T-5A internally and the max [i]average[/i] power is stated as 400W on the back of the amp.
[/quote]

The Streamliner 900 has a stated max average power of 650W, and has an internal 3A fuse, according to the blurb on the back of the amp.
I get confused with those "max average" measurements...

[karlfer]

[quote name='Dad3353' timestamp='1469824194' post='3101388']
Ah... So, Moriarty, you've not read the Manual [i]again[/i], eh..?

[url="http://www.genzbenz.com/img/manuals/gb/Streamliner_600_manual.pdf"]Streamliner 600 Manual ...[/url]
[/quote]

Read?
Manual?

Are you INSANE

[stingrayPete1977]

[quote name='MoonBassAlpha' timestamp='1469812063' post='3101293']
A 3A fuse is not right for an amp that could draw over 900W.
240V * 3A =730W. I'd go for a 10A fuse as stated above.
What is the rating of the internal fuse? My shuttle 6 has a T-5A internally and the max [i]average[/i] power is stated as 400W on the back of the amp.
[/quote]

Input and output wattage have nothing to do with each other, an Ampeg SVT 300 watt head draws 430 watts at 230 volts for example, them valves creating heat and light are wasting power compared to a modern high efficiency amp. A Crown 2500 watt PA amp will take 600 watts at input voltage.

[Chienmortbb]

[quote name='stingrayPete1977' timestamp='1469885865' post='3101785']


Input and output wattage have nothing to do with each other, an Ampeg SVT 300 watt head draws 430 watts at 230 volts for example, them valves creating heat and light are wasting power compared to a modern high efficiency amp. A Crown 2500 watt PA amp will take 600 watts at input voltage.
[/quote]So it can't be a 2500 watt amp then. The point is that anything you connect to the mains will have a surge current when switched on, several times its operating current. So use the recommended fuse and fir an IEC lead it is 10-13 Amps.

[stingrayPete1977]

The input and output voltages are totally different, I have a 130 amp mig welder that has a 13 amp plug top on it.

That crown power amp is rated at 2500 watt OUTPUT 600 watts maximum input.

The fuse is only for the lead so I'd bang a 13 amp in any that has cable and plugs suitable.

Watts= Amps x Volts hence once the power goes through the transformer inside the device it is anyone's guess.

ie- 5 amps x 230 volts = 1150 watts that would be the Input rating on the rear panel (like the 600 on the Crown I mention)

Put that through a transformer and raise the voltage to 920 volts (1-4 ratio primary to secondary windings) and now that same 5 amps at 920 volts would be 4600 watts. To give the same wattage at 230 volts you would then require 4 times the amperage, 20 amps.

Very rough bit of maths, the 2500 watt PA power amp then for example that takes 600 watts at 230 volts is pulling 2.6 amps at 230 volts on the input side, so we know it takes no more than 2.6 amps but peaks at 2500 watts output so the transformer is (very very) roughly producing around 961 volts on the output side of the tranny, this is why you should not poke around in amps!

Edited August 1, 2016 by stingrayPete1977

[4stringslow]

Is that 2500W rating peak or rms?

Watts is a measure of power and while you're quite right that volts and amps can be varied between input and output, depending on the circuitry inside the box, I don't think you can have more power out than goes in. What you can do is measure that power in different ways and marketing people love to use peak power ratings because it gives them a nice big figure for the spec sheet

So if the Crown amp max input is 600W that means 2.6A at 230V (ignoring any AC power factor). If you raise the output voltage using a transformer then the output current will drop because the power MUST remain the same (actually the output power will be somewhat less because the transformer will not be 100% efficient, but that's a detail).

The point is that you cannot get MORE power out than the power input. If you could then you wouldn't have an amp you'd have a power source and have solved the worlds energy problems!

[stingrayPete1977]

[quote name='MoonBassAlpha' timestamp='1469812063' post='3101293']
A 3A fuse is not right for an amp that could draw over 900W.
240V * 3A =730W. I'd go for a 10A fuse as stated above.
What is the rating of the internal fuse? My shuttle 6 has a T-5A internally and the max [i]average[/i] power is stated as 400W on the back of the amp.
[/quote]

My musings are more in response to this to be honest mate, you cant just look at the wattage (900watt in this case) without looking at the voltage, the example above probably takes a fraction of the input wattage suggested.

You can have many more watts out than you put in, but they are at a reduced amperage, the power to move a paper cone isn't much compared to say an electric motor, in that case you might need to reduce the voltage to the point that the input at 3000 watts now only drives a 300 watt motor.

[4stringslow]

Sorry, but I disagree. Yes, the voltage and amps can vary between the input and the output but the point that they BOTH vary such that when you multiply the input volt/amps and the output volt/amps you'll find the power is much the same. I say much the same because no device is 100% efficient so power out will always be less than power in, with the 'lost' power heating things up.

Think about your 130 amp welder with its 13A fused plug. Max input power is 230V x 13A = 2990W. This is the maximum amount of power available to the sharp end of the welder, so if you select a 130A arc then the maximum voltage across that arc will be 2990 / 130 = 23V (again, in practice some power is 'lost' inside the welder as heat because nothing is 100% efficient). This is generally why mains powered arc welders don't electrocute you - because the output voltage is quite low.

Watts are watts, there are no 'reduced amperage' watts. If the amps are reduced, so are the watts, unless the voltage is increased to compensate.

It's basic thermodynamics - you can't get more power (watts) out than you put in.

[obbm]

[quote name='4stringslow' timestamp='1470088591' post='3103268']
Sorry, but I disagree. Yes, the voltage and amps can vary between the input and the output but the point that they BOTH vary such that when you multiply the input volt/amps and the output volt/amps you'll find the power is much the same. I say much the same because no device is 100% efficient so power out will always be less than power in, with the 'lost' power heating things up.

Think about your 130 amp welder with its 13A fused plug. Max input power is 230V x 13A = 2990W. This is the maximum amount of power available to the sharp end of the welder, so if you select a 130A arc then the maximum voltage across that arc will be 2990 / 130 = 23V (again, in practice some power is 'lost' inside the welder as heat because nothing is 100% efficient). This is generally why mains powered arc welders don't electrocute you - because the output voltage is quite low.

Watts are watts, there are no 'reduced amperage' watts. If the amps are reduced, so are the watts, unless the voltage is increased to compensate.

It's basic thermodynamics - you can't get more power (watts) out than you put in.
[/quote]

What he said. Power In (electrical energy) = Power Out (electrical energy + heat)

[karlfer]

I'm so glad I asked.

[4stringslow]

That'll teach you

Funny how even apparently simple things can become quite complex as you zoom in on the detail. As the old saying goes 'the devil is in the detail'