Immunity testing at EMC: How many hours are normal?

[Joerg]

Hello Folks,

Just got an estimate for the immunity part of the compliance tests at an
EMC lab: 21 hours. Ouch! I've never had it that long. Is this normal
these days? What's your recent experience? The data:

DUT: Medical equipment, not life-support but cardio-diagnostic stuff.
Pre-compliance looked great and I am sure we'll ace usual the radiated
and conducted emissions tests.

Included tests would be: AC current harmonics, AC flicker, ESD, radiated
immunity, conducted immunity, magnetic immunity, fast transitions, mains
port surge, voltage dips and interrupts.

I've never had this stuff take more than a day. That's why I am asking
for other opinions.

 

[Nico Coesel]

Hello Folks,

Just got an estimate for the immunity part of the compliance tests at an
EMC lab: 21 hours. Ouch! I've never had it that long. Is this normal
these days? What's your recent experience? The data:

DUT: Medical equipment, not life-support but cardio-diagnostic stuff.
Pre-compliance looked great and I am sure we'll ace usual the radiated
and conducted emissions tests.

Included tests would be: AC current harmonics, AC flicker, ESD, radiated
immunity, conducted immunity, magnetic immunity, fast transitions, mains
port surge, voltage dips and interrupts.

I've never had this stuff take more than a day. That's why I am asking
for other opinions.

That sounds a bit long. Perhaps they have limited space so they need
to reconfigure their lab before doing a different test. A quote from
another lab wouldn't hurt.

 

[Joerg]

That sounds a bit long. Perhaps they have limited space so they need
to reconfigure their lab before doing a different test. A quote from
another lab wouldn't hurt.

It's a big round-the-clock lab and all the stations are permanently set
up. Our system is light, can be hand-carried to the next station by one
strong guy. Any hint what it would have taken in good ol' Europe? My
last time there is almost 20 years ago and susceptibility took less than
a day.

 

[Eeyore]

Hello Folks,

Just got an estimate for the immunity part of the compliance tests at an
EMC lab: 21 hours. Ouch! I've never had it that long. Is this normal
these days? What's your recent experience? The data:

DUT: Medical equipment, not life-support but cardio-diagnostic stuff.
Pre-compliance looked great and I am sure we'll ace usual the radiated
and conducted emissions tests.

Included tests would be: AC current harmonics, AC flicker, ESD, radiated
immunity, conducted immunity, magnetic immunity, fast transitions, mains
port surge, voltage dips and interrupts.

I've never had this stuff take more than a day. That's why I am asking
for other opinions.

Immunity only. Ok, just audio here but we have our own problems such as
setting up representative cabling which can be a right pain. I'm not sure
now how it split but 2 days covered immunity and emissions.

Graham

 

[Joerg]

Immunity only. Ok, just audio here but we have our own problems such as
setting up representative cabling which can be a right pain. I'm not sure
now how it split but 2 days covered immunity and emissions.

So I assume 16 hours of total billed lab time but including emissions.
That sounds similar to my experience. Usually a few flies were found in
the ointment but fixed quickly on the spot so emissions ran into the
next morning but susceptibility was still covered by dusk.

 

[Eeyore]

So I assume 16 hours of total billed lab time but including emissions.
That sounds similar to my experience. Usually a few flies were found in
the ointment but fixed quickly on the spot so emissions ran into the
next morning but susceptibility was still covered by dusk.

That's pretty much it. Last lab I used was Semko (UK).

Graham

 

[Nico Coesel]

It's a big round-the-clock lab and all the stations are permanently set
up. Our system is light, can be hand-carried to the next station by one
strong guy. Any hint what it would have taken in good ol' Europe? My
last time there is almost 20 years ago and susceptibility took less than
a day.

Over here the price is usually 'fixed'. EMC compliance starts at 8000
euro.

 

[legg]

Hello Folks,

Just got an estimate for the immunity part of the compliance tests at an
EMC lab: 21 hours. Ouch! I've never had it that long. Is this normal
these days? What's your recent experience? The data:

DUT: Medical equipment, not life-support but cardio-diagnostic stuff.
Pre-compliance looked great and I am sure we'll ace usual the radiated
and conducted emissions tests.

Included tests would be: AC current harmonics, AC flicker, ESD, radiated
immunity, conducted immunity, magnetic immunity, fast transitions, mains
port surge, voltage dips and interrupts.

I've never had this stuff take more than a day. That's why I am asking
for other opinions.

Sounds like they don't want your business.

RL

 

[Joerg]

Over here the price is usually 'fixed'. EMC compliance starts at 8000
euro.

Hmm, in the 90's it used to be around 8000 Deutschmarks or about half.
Getting the truck there was a major cost factor because of the Diesel
prices over there ;-)

Does that include the usual AC line tortures and ESD?

 

[Joerg]

Sounds like they don't want your business.

Oh, they do. What are the prices/hours like up there in Canada?

 

[Eeyore]

Sounds like they don't want your business.

Joerg should send them a letter to that effect !


Graham

 

[Joerg]

Joerg should send them a letter to that effect !

My client would have to. We will have a meeting to that effect

 

[legg]

legg wrote:

Oh, they do. What are the prices/hours like up there in Canada?

The price/hour varies per facility/standard (and location to some
extent). Anything rushed costs more, if its even possible. Always
schedule well in advance and have all hardware ready on-site well
before the due date.

Last MIL emc/immunity took 5hrs on-site + reporting hours.

Last Telecom emc/immunity took 4hrs + reporting time.

In both cases these were attended - meaning a body was there to apply
relevent hardware and make sure the DUT(s) was/were servicable and to
witness that the test methods were in line with the the applicable
standards. No all labs are happy with this, but some prefer it. It has
it's own costs.

I expect it could have taken longer in either case, if there was a
hard failure or no-pass at some point (the Mil test involved a half
hour of screwing around looking for a leaking birdie). Such an event
adds setup hours and non-chargeable program delays.

With omploding manufacturing in this area, perhaps local test houses
have periods where they're under-utilized. It is a strangely seasonal
activity, even under normal economic conditions, so you might get
better rates/service by arranging to use any slack periods.

RL

 

[Nico Coesel]

Hmm, in the 90's it used to be around 8000 Deutschmarks or about half.
Getting the truck there was a major cost factor because of the Diesel
prices over there ;-)

Does that include the usual AC line tortures and ESD?

IIRC only ESD is included.

 

[John Devereux]

Hello Folks,

Just got an estimate for the immunity part of the compliance tests at
an EMC lab: 21 hours. Ouch! I've never had it that long. Is this
normal these days? What's your recent experience? The data:

DUT: Medical equipment, not life-support but cardio-diagnostic
stuff. Pre-compliance looked great and I am sure we'll ace usual the
radiated and conducted emissions tests.

Included tests would be: AC current harmonics, AC flicker, ESD,
radiated immunity, conducted immunity, magnetic immunity, fast
transitions, mains port surge, voltage dips and interrupts.

I've never had this stuff take more than a day. That's why I am asking
for other opinions.

Presumably the standard says that the device must continue working
correctly during the interference - how long does it take to verify
that the device works? Does this need to be done, for example, for
each of a series of frequencies?

 

[Joerg]

The price/hour varies per facility/standard (and location to some
extent). Anything rushed costs more, if its even possible. Always
schedule well in advance and have all hardware ready on-site well
before the due date.

We usually do that.

Last MIL emc/immunity took 5hrs on-site + reporting hours.

Last Telecom emc/immunity took 4hrs + reporting time.

Wow, that is really fast.

In both cases these were attended - meaning a body was there to apply
relevent hardware and make sure the DUT(s) was/were servicable and to
witness that the test methods were in line with the the applicable
standards. No all labs are happy with this, but some prefer it. It has
it's own costs.

We always do that. There are usually 2-3 engineers from our side
present. Not so much to watch the MEC engineer but in case something
goes kablouie or a quick fix for a leak is needed.

I expect it could have taken longer in either case, if there was a
hard failure or no-pass at some point (the Mil test involved a half
hour of screwing around looking for a leaking birdie). Such an event
adds setup hours and non-chargeable program delays.

Unfortunately many sites are in congested areas sucha as Silicon Valley.
tons of ambient RF. I prefer the boonies, much faster. Plus there's
usually a good saloon in town with country dancing and all that ;-)

 

[Joerg]

Presumably the standard says that the device must continue working
correctly during the interference - how long does it take to verify
that the device works? Does this need to be done, for example, for
each of a series of frequencies?

That's one of the things I'll have to find out, whether the EMC lab want
to go a bit overboard. Figuring out whether the device works correctly
often requires special software but once that is in place you have an
almost instant indicator. I just don't see 21 hours here.

 

[legg]

We usually do that.



Wow, that is really fast.

It helps if you run some tests at the same time that automated sweep
data is collected. Differing tests can be applied to devices with
different serial numbers, providing the construction is uniform.
Not always practical for larger or more esoteric ($$) devices, but I
figured the cost-conscious OP was dealig with a jellybean, albeit
'biomedical' one.

It's also possible to miss something that turns out not to be kosher
during report generation. Care is needed in all prior stages.

RL

 

[legg]

That's one of the things I'll have to find out, whether the EMC lab want
to go a bit overboard. Figuring out whether the device works correctly
often requires special software but once that is in place you have an
almost instant indicator. I just don't see 21 hours here.

If the product testing is as error-free as you expect, then you
obviously would only get charged for the facility and man-hours that
are consumed. If you've not done business with the house involved,
they could just be assuming the worst, based on the last similar
device tested.

A tight schedule at the test house means that trouble-free evaluation
frees the facility to clear backlog.

RL