AC protection equipment for enginner

[eeh]

Hi,

Recently I need to control Triac by MCU. I wonder if there exists some
protection equipments to develop these kind of embedded system such as
current limiting of main AC as I am just a beginner.

Thanks!

 

[Wim Ton]

Hi,

Recently I need to control Triac by MCU. I wonder if there exists some
protection equipments to develop these kind of embedded system such as
current limiting of main AC as I am just a beginner.

Put a toaster, electric iron or room heater in series with your device. It
will limit current to a level that the mains fuse would not blow.

Use a variable transformer (variac) to ramp up the voltage slowly, so you
have time to switch the circuit off when things start smoking

Use an insulation transformer to avoid having all your equipment connected
to the mains.

Wim

 

[Tim Mitchell]

Put a toaster, electric iron or room heater in series with your device. It
will limit current to a level that the mains fuse would not blow.

Use a variable transformer (variac) to ramp up the voltage slowly, so you
have time to switch the circuit off when things start smoking

Use an insulation transformer to avoid having all your equipment connected
to the mains.

Use a transformer to run the circuit at 24V ac until you are confident
the design is OK. The triac will work the same at the lower voltage.

 

[Spehro Pefhany]

Hi,

Recently I need to control Triac by MCU. I wonder if there exists some
protection equipments to develop these kind of embedded system such as
current limiting of main AC as I am just a beginner.

Thanks!

You can put a light bulb in series with the circuit.

BUT the most important thing is to use an isolation transformer! This
is at no time more important than if your circuit does not have
isolation itself. You leave both sides of the AC power on the other
side of the isolation transformer floating wrt ground. Otherwise a
single point fault can take out your circuit, any emulators and other
expensive equipment that you're using, and perhaps even computers that
are connected to it. It could also give you a nasty (perhaps fatal)
shock much more easily.


Best regards,
Spehro Pefhany

 

[Keith Williams]

Hi,

Recently I need to control Triac by MCU. I wonder if there exists some
protection equipments to develop these kind of embedded system such as
current limiting of main AC as I am just a beginner.

Use optical isolators (or isolating triac) to isolate the AC from the
MCU. Run the MCU off a wall-wart.

 

[colin]

Hi,

Recently I need to control Triac by MCU. I wonder if there exists some
protection equipments to develop these kind of embedded system such as
current limiting of main AC as I am just a beginner.

I usualy rely on my wits to protect me although i have learned the hard way
to clearly mark any mains plugs/leads used to conect the equipment under
test to the mains

as other posts have sugested bulbs in series etc also variac and isolation
transformer of course. dont forget that about only a mere 20ma at mains
voltage is considered enough to be hazardous to health.

fusible resistors can also be a help as they initialy limit the curent and
also disconect it
(any metal film resistor will fuse at high overload, puting a sleave over it
wil stop bits hiting you in the face when it explodes) you can also get re
setable curent trip devices.

other personal safety devices often get tripped far too easily if you have
much in the way of interfence supresion or scopes conected to it etc.

Colin =^.^=

 

[Ian Stirling]

Use a transformer to run the circuit at 24V ac until you are confident
the design is OK. The triac will work the same at the lower voltage.

The triac may work the same at the lower voltage.
There are a number of issues that might bite you and make it not.
It's a good idea first, as it's unlikely that if it doesn't work on 24V,
it won't work on 100/120/240/415/...