[Emc-users] OT - handling a 120v ac dip

[k***@gmail.com]

I am just a tinkerer so I'm looking for advice. I have a project using an
ESP8266 to control a light. I am using a Panasonic AQY280EH to switch the
light. What is the safe protocol for mounting and connecting a device that
is using a high voltage.

[Gene Heskett]

Post by k***@gmail.com
I am just a tinkerer so I'm looking for advice. I have a project using
an ESP8266 to control a light. I am using a Panasonic AQY280EH to
switch the light. What is the safe protocol for mounting and
connecting a device that is using a high voltage.

One normally uses an opto-isolator to separate the computer from the high
voltages in the external world. Wire the + terminal of the led in the
isolator, with a current limiting resistor to a 5 volt supply, and wire
the - terminal of the led to the control output. You want to "pull"
the - terminal to a logic zero to turn on the led because thats the more
capable direction in terms of the current needed to turn on the led.
The other 2 terminals of the isolator are connected, aka "on" when the
led shines on the other side, with a high voltage, usually up to 5,000
volts, of isolation, between the two parts of the isolator. And
generally, when the led is energized, the circuit on the other side of
the air gap will be too.

The output side may or may not be polarity sensitive, and if it is, will
also have + and - markings.

You can get ready made kits for 1 or 4 on a board, of such devices from
ebay for quite nominal prices. I just wired up one channel of a 4
channel I had in the spares drawer, to pull the RST terminal of the VFD
running my lathes spindle down to its control ground so I didn't have to
get a step-stool to reset it by hand in the event it faults. A .4
second reset pulse sent by the pi running things works fine.

Those generally are made for various input and output voltages, so you
buy them accordingly. This one expects a 5 volt input, and controls the
12 volt swing inputs of the VFD. The VFD supplies the 12 volts needed,
as well as its local ground/common. Unfortunately, those are common on
this particular kit so I can't use it as 4 independent output channels.

Cheers, Gene Heskett

[Ralph Stirling]

The AQY280EH is optically isolated, but can only switch a low current load (130mA). If you are switching a 60w bulb, you would need a several amp device to handle the in-rush current of a cold bulb. I like to wire a "puck" type solid state relay (ssr) into an old metal outlet strip (that can be opened up, and that has room inside) or into a 4x4 metal junction box with a receptacle and cord. A couple of small wires can be brought out for the low voltage control.

If you need more detail, I can dig up some example ssr part numbers and sketch out the simple circuit for you.

-- Ralph

On Jun 21, 2017 12:03 PM, ***@gmail.com wrote:
I am just a tinkerer so I'm looking for advice. I have a project using an
ESP8266 to control a light. I am using a Panasonic AQY280EH to switch the
light. What is the safe protocol for mounting and connecting a device that
is using a high voltage.

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[andy pugh]

Post by Ralph Stirling
I like to wire a "puck" type solid state relay (ssr)

There are lots of these on eBay: http://www.ebay.co.uk/itm/201370409744 for
example

Most of these are fake. For example one I bought rated 40A contained an 16A
device.
But then, when you compare to a genuine 15A device, they are still quite
cheap:
http://www.mouser.co.uk/ProductDetail/Crydom/RPC2415
Of course, the rest of the engineering in the eBay fakes is probably
equally bogus.

[Gene Heskett]

Post by Ralph Stirling
The AQY280EH is optically isolated, but can only switch a low current
load (130mA). If you are switching a 60w bulb, you would need a
several amp device to handle the in-rush current of a cold bulb. I
like to wire a "puck" type solid state relay (ssr) into an old metal
outlet strip (that can be opened up, and that has room inside) or into
a 4x4 metal junction box with a receptacle and cord. A couple of
small wires can be brought out for the low voltage control.
If you need more detail, I can dig up some example ssr part numbers
and sketch out the simple circuit for you.

I am using a similar circuit, 2 SSR's wide, to switch both sides of the
254 volt feed that powers the VFD and stepper supplies on this Sheldon
lathe. These are the 40 amp versions because there is a considerable
inrush when powering up the supplies. mpja.com has several sizes of such
devices, all of which can be controlled by the 3 volt or more signal
from most any breakout board.

Because the inrush was so high on my mill, I had to soft start the
spindle motor supply else it would trip a 20 amp breaker starting it.
So the first stage starts with a 100 ohm 200 watt resistor to limit the
current, then about 4 seconds later, enables the 2nd SSR which connects
it directly. The mill, working, draws about 3.5 amps.

Big SSR's are handy, so I keep at least 2 in the spare parts drawer.

Post by Ralph Stirling
-- Ralph
I am just a tinkerer so I'm looking for advice. I have a project using
an ESP8266 to control a light. I am using a Panasonic AQY280EH to
switch the light. What is the safe protocol for mounting and
connecting a device that is using a high voltage.
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Cheers, Gene Heskett

[Gene Heskett]

Post by Gene Heskett
Big SSR's are handy, so I keep at least 2 in the spare parts drawer.

And I should append that all of them I have used were born in China, and
I have yet to destroy any of them. The 2 in the spare parts drawer are
for my next wild idea. ;-)

Cheers, Gene Heskett