Re: [Emc-users] SSR Issues, Thyristor dv/dt

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

Re: [Emc-users] SSR Issues, Thyristor dv/dt

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

Re: [Emc-users] SSR Issues, Thyristor dv/dt

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 <el...@pico-systems.com> wrote: > >

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 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:

Re: [Emc-users] SSR Issues, Thyristor dv/dt

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

Re: [Emc-users] SSR Issues, Thyristor dv/dt

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

Re: [Emc-users] SSR Issues, Thyristor 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

Re: [Emc-users] SSR Issues, Thyristor dv/dt --> Inrush current?

> > 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

Re: [Emc-users] SSR Issues, Thyristor dv/dt

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

Re: [Emc-users] SSR Issues, Thyristor dv/dt

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

Re: [Emc-users] SSR Issues, Thyristor dv/dt

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

Re: [Emc-users] SSR Issues, Thyristor dv/dt

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,

Re: [Emc-users] SSR Issues, Thyristor dv/dt

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

Re: [Emc-users] SSR Issues, Thyristor dv/dt

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

Re: [Emc-users] SSR Issues, Thyristor dv/dt

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

Re: [Emc-users] SSR Issues, Thyristor dv/dt

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,

Re: [Emc-users] SSR Issues, Thyristor dv/dt --> Inrush current?

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

Re: [Emc-users] SSR Issues, Thyristor dv/dt

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

Re: [Emc-users] SSR Issues, Thyristor dv/dt

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 >

Re: [Emc-users] SSR Issues, Thyristor dv/dt

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

Re: [Emc-users] SSR Issues, Thyristor dv/dt

> > > 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 > > >

Re: [Emc-users] SSR Issues, Thyristor dv/dt --> Inrush current?

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

Re: [Emc-users] SSR Issues, Thyristor dv/dt

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 >

Re: [Emc-users] SSR Issues, Thyristor dv/dt

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

Re: [Emc-users] SSR Issues, Thyristor dv/dt

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

Re: [Emc-users] SSR Issues, Thyristor dv/dt

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

Re: [Emc-users] SSR Issues, Thyristor dv/dt

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

Re: [Emc-users] SSR Issues, Thyristor dv/dt

> 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

Re: [Emc-users] SSR Issues, Thyristor dv/dt

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 >

Re: [Emc-users] SSR Issues, Thyristor dv/dt

> 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

Re: [Emc-users] SSR Issues, Thyristor dv/dt

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

Re: [Emc-users] SSR Issues, Thyristor dv/dt

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

Re: [Emc-users] SSR Issues, Thyristor dv/dt

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

Re: [Emc-users] SSR Issues, Thyristor dv/dt

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.

Re: [Emc-users] SSR Issues, Thyristor dv/dt

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:

Re: [Emc-users] SSR Issues, Thyristor dv/dt

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

Re: [Emc-users] SSR Issues, Thyristor dv/dt

> 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

Re: [Emc-users] SSR Issues, Thyristor dv/dt

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

Re: [Emc-users] SSR Issues, Thyristor dv/dt

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