That was a funny eBay search.
According to Fotek the DC to DC version is SSR-40DD
eBay search for SSR-40DD shows many DC-rated SSRs for 60VDC output.
But I would be wanting 600V rating, and that ought to be a -H suffix.
SSR-40DD-H as an eBay search seems to show things very unrelated to
SSRs. I
On 4 May 2016 at 12:33, Steve Stallings wrote:
> We have been the victim of counterfeit Fotek SSR units. They
> looked fine, but required over 6 volts input to turn them on.
Have you pulled any apart to see what Triac they use?
You might be able to tell real Fotek from fake by weight, I am prett
nal Message-
> From: andy pugh [mailto:bodge...@gmail.com]
> Sent: Wednesday, May 04, 2016 6:38 AM
> To: Enhanced Machine Controller (EMC)
> Subject: Re: [Emc-users] SSR Issues, Thyristor dv/dt
>
> On 4 May 2016 at 02:38, Jon Elson wrote:
> > OH WELL, there you have it! A 1
On 4 May 2016 at 02:38, Jon Elson wrote:
> OH WELL, there you have it! A 16 A triac in a 40 A labeled
> SSR! If there's one bogus thing in a device, you can depend
> on the WHOLE thing having bogus engineering.
Here is an analysis of one from bigclive:
https://www.youtube.com/watch?v=DxEhxjvify
On 05/03/2016 12:39 PM, andy pugh wrote:
> On 3 May 2016 at 18:16, Jon Elson wrote:
>> Are these name-brand SSRs
>> or some china noname units you got on eBay?
> Well, the labels say "Fotek" but then the labels are peeling off, and
> I today found web pages talking about fake Fotek SSRs.
>
> Havin
This is clearly ancient history but: many years ago in a time before
time
a guy needed a CC device to light orchard heaters. Nichrome coiled
elements in series; must touch off either oil or propane. It used an
off-the-shelf SCR feeding (ugh!) an 240 v to 440 v transformer.
Indeed the dv/dt'
On 3 May 2016 at 18:16, Jon Elson wrote:
> Are these name-brand SSRs
> or some china noname units you got on eBay?
Well, the labels say "Fotek" but then the labels are peeling off, and
I today found web pages talking about fake Fotek SSRs.
Having taken one apart, the triac in my 40-Amp SSR is a
> > If you need limiting of inrush current I guess a transistor connected as a
> > current source would be the perfect solution for this? Or is it against
> > surge voltage?
>
> The reason I need inrush current limiting is mainly so that the lights
> and fridge stay on when I turn on the lathe :
On 05/03/2016 07:46 AM, andy pugh wrote:
> On 3 May 2016 at 13:37, Gene Heskett wrote:
>>> And does the "fail to turn off" problem description include not
>>> turning off ever again, even when removed from the circuit and from
>>> all power?
>> Generally yes, its an avalanche mode failure that sho
On 05/03/2016 06:14 AM, andy pugh wrote:
> I could pick a couple of these up today, though it is an 80-mile round
> trip. I wonder if they would work better?
> http://www.rapidonline.com/kudom-ksim380d25-l-panel-mount-ssr-4-32vdc-48-440vac-25a-load-led-zero-cross-60-1598
> (For a total of 2kW of se
On 05/03/2016 05:42 AM, andy pugh wrote:
it sounds like your derating should have been sufficient.
The fact that an SSR with a SIZEABLE resistor in series with
it failed is awfully suspicious! Are these name-brand SSRs
or some china noname units you got on eBay?
While the nonlinear nature of t
On 3 May 2016 at 15:12, John Kasunich wrote:
> The vast majority of the AC drives on the market don't even have a
> pre-charge contactor. When power is applied, the bus immediately
> charges thru the resistor.
And that would be perfectly acceptable in my application too, thinking
about it, thoug
On Tue, May 3, 2016, at 10:00 AM, andy pugh wrote:
> If there is no reason not to leave the pre-charge relay closed during
> operation, I could even use the existing mechanical relay that brings
> in the discharge resistor. Is there a reason to switch-out the
> precharge relay once the main conta
On 3 May 2016 at 14:31, John Kasunich wrote:
>
> Is there any particular reason you are using SSRs instead of
> regular contactors? I like contactors because they are rugged
> and pretty much immune to overvoltage, dv/dt, and di/dt problems.
Mainly it is a matter of available space (or became su
On Tue, May 3, 2016, at 09:34 AM, andy pugh wrote:
> On 3 May 2016 at 14:27, Erik Christiansen wrote:
> > Yup, a MOV goes across the triac, to clamp voltage spikes.
>
> When you say "Across" do you mean across the output terminals of the
> SSR, or between the live terminal of the SSR and neutra
On Tuesday 03 May 2016 08:46:07 andy pugh wrote:
> On 3 May 2016 at 13:37, Gene Heskett wrote:
> >> And does the "fail to turn off" problem description include not
> >> turning off ever again, even when removed from the circuit and from
> >> all power?
> >
> > Generally yes, its an avalanche mode
On 3 May 2016 at 14:00, Nicklas Karlsson wrote:
> If you need limiting of inrush current I guess a transistor connected as a
> current source would be the perfect solution for this? Or is it against surge
> voltage?
The reason I need inrush current limiting is mainly so that the lights
and fri
On 3 May 2016 at 14:27, Erik Christiansen wrote:
> Yup, a MOV goes across the triac, to clamp voltage spikes.
When you say "Across" do you mean across the output terminals of the
SSR, or between the live terminal of the SSR and neutral?
The former is easier, and I doubt that there would be much
On Tue, May 3, 2016, at 06:42 AM, andy pugh wrote:
> Section 6 on page C-343 here:
> https://www.omron.com/ecb/products/pdf/precautions_ssr.pdf shows a
> square-wave with zero time at 0 current. But I don't understand how
> that is possible with a sinusoidal input voltage. Surely the current
> is
On 03.05.16 13:32, andy pugh wrote:
> On 3 May 2016 at 13:29, andy pugh wrote:
> > Until I googled just now I thought that this was what was meant by
> > MOV. The data sheets for Varistors seem to specify an activation
> > voltage and a power dissipation, but no off-state resistance
> > measuremen
> > > If Solid State Relay SSR happen to be a thyristor it will only allow
> > > a limited dv/dt or it will fail to turn off. A common source of
> > > dv/dt is inductive or maybe capacitive load and it happens because a
> > > thyristor turn off at zero current although a reactive load do not
> > >
On 3 May 2016 at 13:57, Nicklas Karlsson wrote:
>> You may need higher voltage rated devices, Andy. Without ANY switching
>> spikes, or the EMP from a nearby lightning strike, they are seeing the
>> RMS peak voltage of 338.4 volts (240 * 1.41) 100 times a second.
>
> Yes you are correct 240Vac*sq
On Tue, 3 May 2016 13:29:42 +0100
andy pugh wrote:
> On 3 May 2016 at 12:41, Erik Christiansen wrote:
> >
> > The link to SSR precautions indicates that the SSR already includes a
> > snubber. But page 3 of the notes says that is often not sufficient, and
> > suggests a 440 - 470 volt varistor (
> On Tuesday 03 May 2016 04:54:32 andy pugh wrote:
>
> > On 3 May 2016 at 02:51, Jon Elson wrote:
> > > You should very conservatively derate the SSRs
> > > in many circumstances, but especially where capacitive
> > > inrush surge is possible.
> >
> > The PSU is powered through a 20A breaker and
On 3 May 2016 at 13:37, Gene Heskett wrote:
>> And does the "fail to turn off" problem description include not
>> turning off ever again, even when removed from the circuit and from
>> all power?
>
> Generally yes, its an avalanche mode failure that shorts the switching
> junction.
I am not 100%
On Tuesday 03 May 2016 06:40:35 Erik Christiansen wrote:
> On 03.05.16 10:30, andy pugh wrote:
> > And does the "fail to turn off" problem description include not
> > turning off ever again, even when removed from the circuit and from
> > all power?
>
> No, dv/dt triggering is merely spurious init
On 3 May 2016 at 13:29, Nicklas Karlsson wrote:
> If possible I would measure voltage spike before to make sure there are any
> otherwise the problems is elsewhere.
I have no real reason to think that I have a voltage spike problem at
all, really. I don't think I have ever had an appliance fail
On Tuesday 03 May 2016 05:30:54 andy pugh wrote:
> On 3 May 2016 at 10:14, Nicklas Karlsson
wrote:
> > If Solid State Relay SSR happen to be a thyristor it will only allow
> > a limited dv/dt or it will fail to turn off. A common source of
> > dv/dt is inductive or maybe capacitive load and it h
On 3 May 2016 at 13:29, andy pugh wrote:
> Until I googled just now I thought that this was what was meant by
> MOV. The data sheets for Varistors seem to specify an activation
> voltage and a power dissipation, but no off-state resistance
> measurement to calculate the power dissipation. Or is th
> On 03.05.16 12:14, andy pugh wrote:
> > I could pick a couple of these up today, though it is an 80-mile round
> > trip. I wonder if they would work better?
> > http://www.rapidonline.com/kudom-ksim380d25-l-panel-mount-ssr-4-32vdc-48-440vac-25a-load-led-zero-cross-60-1598
>
> Well, 620v peak oug
On 3 May 2016 at 12:41, Erik Christiansen wrote:
>
> The link to SSR precautions indicates that the SSR already includes a
> snubber. But page 3 of the notes says that is often not sufficient, and
> suggests a 440 - 470 volt varistor (MOV) as protection in a 200 - 240
> volt application. That clea
On Tuesday 03 May 2016 04:54:32 andy pugh wrote:
> On 3 May 2016 at 02:51, Jon Elson wrote:
> > You should very conservatively derate the SSRs
> > in many circumstances, but especially where capacitive
> > inrush surge is possible.
>
> The PSU is powered through a 20A breaker and the SSRs are rat
> On 03.05.16 11:42, andy pugh wrote:
> > On 3 May 2016 at 10:41, Nicklas Karlsson
> > wrote:
> > > In other words i/C should be less than maximum allowed du/dt.
> >
> > I am not sure how to determine the i for this calculation. I guess I
> > can find the dv/dt from the component numbers on this
On 03.05.16 12:14, andy pugh wrote:
> I could pick a couple of these up today, though it is an 80-mile round
> trip. I wonder if they would work better?
> http://www.rapidonline.com/kudom-ksim380d25-l-panel-mount-ssr-4-32vdc-48-440vac-25a-load-led-zero-cross-60-1598
Well, 620v peak ought to give s
On 03.05.16 11:42, andy pugh wrote:
> On 3 May 2016 at 10:41, Nicklas Karlsson wrote:
> > In other words i/C should be less than maximum allowed du/dt.
>
> I am not sure how to determine the i for this calculation. I guess I
> can find the dv/dt from the component numbers on this page:
> http://w
I could pick a couple of these up today, though it is an 80-mile round
trip. I wonder if they would work better?
http://www.rapidonline.com/kudom-ksim380d25-l-panel-mount-ssr-4-32vdc-48-440vac-25a-load-led-zero-cross-60-1598
(For a total of 2kW of servo drive a 25A device ought to be
sufficient, I
On 3 May 2016 at 11:42, andy pugh wrote:
>
> In case it helps, this is the input circuit.
> https://imagebin.ca/v/2fs1b7szpsMy The SSRs are controlled by LinuxCNC
> individually.
That left out an important part of the circuit
https://imagebin.ca/v/2fs60d4YbDyo is better.
--
atp
"A motorcy
On 3 May 2016 at 10:41, Nicklas Karlsson wrote:
> In other words i/C should be less than maximum allowed du/dt.
I am not sure how to determine the i for this calculation. I guess I
can find the dv/dt from the component numbers on this page:
http://www.instructables.com/id/The-inner-workings-of-Co
On 03.05.16 10:30, andy pugh wrote:
> And does the "fail to turn off" problem description include not
> turning off ever again, even when removed from the circuit and from
> all power?
No, dv/dt triggering is merely spurious initiation of conduction by
excessively rapid increase of applied voltage
> On 3 May 2016 at 10:14, Nicklas Karlsson wrote:
> > If Solid State Relay SSR happen to be a thyristor it will only allow a
> > limited dv/dt or it will fail to turn off. A common source of dv/dt is
> > inductive or maybe capacitive load and it happens because a thyristor turn
> > off at zero
On 3 May 2016 at 10:14, Nicklas Karlsson wrote:
> If Solid State Relay SSR happen to be a thyristor it will only allow a
> limited dv/dt or it will fail to turn off. A common source of dv/dt is
> inductive or maybe capacitive load and it happens because a thyristor turn
> off at zero current al
If Solid State Relay SSR happen to be a thyristor it will only allow a limited
dv/dt or it will fail to turn off. A common source of dv/dt is inductive or
maybe capacitive load and it happens because a thyristor turn off at zero
current although a reactive load do not have zero voltage at zero c
On 3 May 2016 at 03:04, Gene Heskett wrote:
> You may have been tapped by the EMP of a nearby lightning strike, Andy.
The machine has been disconnected from the mains pretty much all the
time since it last worked.
In fact the PSU has only been wired-in for a few weeks, and I don't
think we have h
On 3 May 2016 at 02:51, Jon Elson wrote:
> You should very conservatively derate the SSRs
> in many circumstances, but especially where capacitive
> inrush surge is possible.
The PSU is powered through a 20A breaker and the SSRs are rated at 40A.
The anticipated peak motor current is about 12A t
FWIW, this is the authorized Automation Direct distributor in the UK.
http://www.lamonde.com/acatalog/Timer_Switches_Timer_Relays.html
These are interesting also but I have only used a few of them. So far so
good.
http://www.lamonde.com/acatalog/WEG-Electric-Miniature-Contactors--3-Pole-.html
T
On Monday 02 May 2016 19:17:41 andy pugh wrote:
> The PSU on my lathe is something I made myself. On the input side are
> two SSRs, one for power on/off and the other switches-out a soft-start
> resistor.
> There is also s discharge capacitor that is switched in when the main
> input SSR is switch
On Mon, May 2, 2016 at 9:05 PM, andy pugh wrote:
> I don't think I have a collapsing field. Downstream of the relay is a
> rectifier and a big capacitor.
I would like to see a good reference on this. I have some homebuilt
equipment with SSR's switching power supplies and never had any
problem.
I've had problems with SSRs shorting out in certain applications.
Because of that I limit the use of SSRs to simply switching power to a
load and that is it.
For instance; they are very useful for driving heaters for time
proportioned outputs schemes to control heat output.
I also use them when s
On 05/02/2016 06:17 PM, andy pugh wrote:
>
> Today things went a bit strange, blowing the breaker and then the
> discharge resistor. This was with the PSU powered up, but not turned
> on.
>
> It turns out that I have an unanticipated failure mode, if both input
> SSRs fail closed-circuit.
>
> I hav
On 3 May 2016 at 02:05, andy pugh wrote:
> knows a good place to ask.
Addendum: Good places would be places where the question gets answered
with reasoned arguments, not statements that "that is not to code"
(unless backed up with an explanation about what the code is based
on).
(Sorry, had a ba
On 3 May 2016 at 01:11, Eric Keller wrote:
> I can guarantee that an
> undergraduate mechanical engineering student isn't even going to
> suspect that there is going to be an issue. What I realized is that I
> know how to deal with a collapsing field with a DC relay, but not with
> an AC circuit.
I recently ran into a similar problem in a design class I was
teaching. As a mechanical engineer, I have to admit that I don't
always think these things through, and I can guarantee that an
undergraduate mechanical engineering student isn't even going to
suspect that there is going to be an issue.
52 matches
Mail list logo
