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Author Topic: Ameritron warning-UPDATE  (Read 40582 times)
AH6RR
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Posts: 846




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« Reply #30 on: October 14, 2013, 05:08:54 PM »

This is most likely is how they will get away with it.


Caution: This amplifier must be disconnected from t
he power mains before removing the cover. See the
warning on page 16.


WARNING!!!
MAKE NO ATTEMPT TO PUT THIS AMPLIFIER IN SERVICE WI
TH THE COVER REMOVED! CONTACT
WITH VOLTAGES INSIDE THIS AMPLIFIER CAN BE FATAL!
 
ALWAYS DISCONNECT THE AMPLIFIER
FROM THE POWER MAINS AND WAIT FOR THE FILTER
CAPACITORS TO DISCHARGE BEFORE
REMOVING THE COVER.
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W9FIB
Member

Posts: 2531




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« Reply #31 on: October 16, 2013, 02:01:56 AM »

It is just like the warning on McDonalds coffee cups. It states the obvious because it is true. But without the warning, there are always those who can claim damages because the obvious was not obvious to them. Or so they say.
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73, Stan
Wisdom is knowledge you gain after you know it all.
W1QJ
Member

Posts: 2990




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« Reply #32 on: October 16, 2013, 04:35:54 AM »

OK, I contacted Ameritron and had several email exchanges with MIKE.  He says they were aware of the problem and thanked me for bringing it to his attention.  He did not say when, but he did say that they are now making the fix so this voltage is not present.  I assume whatever is coming out now should be free of this problem.  That is as far as I went with that issue.  I asked him if it would be too much trouble to wire that circuit according to the schematic and he said he would look into that.  To fix the problem is simple, it requires moving one wire.   As for amplifier certification'  I am in the process of certifying our Lunar Link LA-62 6 meter amplifier. Most if not all testing will be done in our own lab.  Self certification is possible if the equipment you are using is acceptable to the FCC.  A list of the equipment you are using along with photographs of the equipment and the unit under test is shown in the photographs you can self certify 100%.  Now although I have not gotten to the point where I have submitted any of this, we do have a test lab suitable for self certification.  It is pubic domain to download others information submitted for their amplifier certification.  We have chosen a "model" certification presentation that has passed FCC regs. and will be using that model to submit for our testing data.  In the early stages of my work, I can see that most of the concern of the FCC is RF wise with purity of the emissions.  Harmonic and IMD specs are high on the list.  15db gain max.  and things like that.  I don't see anywhere in the requirements for interlocks and the like.  There may be something I have not seen yet that requires some sort of attesting to in regard to the low voltage and line voltage safety.  As I move further into this process I can keep you updated with the trials and tribulations.  In the short run it seems pretty straight forward as long as your unit will meet the regulations.  K1FO the original designer of our product was very concerned about  emissions of all his amplifier line, although there are no regulations above 144mhz.  Our 144,220,and 432 amps all have harmonic filters on them.  Our whole line of amps run on a pair of 3CX800 or 3CPx800 tubes.   Our 6 meter amp is the only one that needs certifying.  I'll have more information on this as time goes on and we move through the process.  K1FO had already performed the data necessary and as I reviewed it, the unit should pass with no problem.  More as it happens.  If you are not familiar with Lunar Link amps, you can visit our website at www.lunarlink.com  Lou
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KH6AQ
Member

Posts: 8008




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« Reply #33 on: October 16, 2013, 08:11:42 AM »

W1QJ,

your amp needs to be designed to the applicable safety standard. UL60950 seems to be the default standard for equipment that does not fall neatly into another standard. You should purchase a copy of UL60950-1 but if you look around on the web there are pirated copies to be found.

The Ameritron amps are not a good example of how to meet UL60950 or EN60950 or to obtain the CE mark as they are (in my opinion) not fully compliant.

Redesigning to meet safety can be expensive and it pays to do it right the first time. It's not hard to do. My comments here are not complete and may contain errors. They are meant only to get you thinking about what is needed as you read UL60950-1. The bottom line is that given a "single fault" (one component opening or shorting) the unit will not present a shock or fire hazard. UL60950, like every safety standard I've seen, is difficult to follow and seems to be open to interpretation in spots. It can cost $10,000 to have your unit looked over and blessed yet takes only a few hours.  

If you want to pay for consulting on this I can give you the contact information of someone who does this. I do safety design but usually defer to someone who does it full time.  

Bonding. The screw attaching the AC ground must not be able to be loosened from outside the enclosure.
The unit (if intended to be plugged into a 20 amp AC circuit) must support 30 A RMS for 2 minutes with a voltage drop of no more than 2 volts. This current is applied between the AC power GND and any conductive point on the enclosure. To obtain the CE mark the AC ground wiring must be green/yellow stripped.

Y-caps (EMI caps from Line-to-GND or Neutral-to-GND) must be "safety rated." These caps are not included in the "single fault" analysis.

100% of units sold must be Hipot tested. 2121 VDC is applied to Line/Neutral for 1 minute.

Do not use MOVs. These are not needed in a properly designed unit and they complicate the Hipot test (they must be disconnected for Hipot) and they now require series fuses.

Creepage and Clearance (spacing between Line-to-GND, neutral-to-GND, and line-to-neutral).

AC wiring must be double insulated. It is acceptable to slip heat shrink tubing over each AC wire.

Touch Current (current from chassis to GND with the chassis not grounded) must not exceed 3.5 mA. This limits the Y-caps to 68 nF. They should be smaller than this to reduce nuisance tripping of GFIs.

UL60950-1, page 101 describes Safety Interlocks. Quoting page 101:

"SAFETY INTERLOCKS shall be provided where OPERATOR access involves areas normally presenting
hazards in the meaning of this standard."

My interpretation is that because the user may access the HV area to change tubes, a HV Safety Interlock is required.

I believe 100% testing of this feature is required. That is, every amp sold must have the HV Safety Interlock tested.

Line impulse test. This is not a problem and it taken care of with a line-to-neutral capacitor.

Thermal. The fan must be stalled (locked rotor test) and the fan and the unit must not get too hot, cause a fire, and any primary transformer windings must not exceed the temperature rating of their insulating materials. Temperature sensors, fan rotation sensors, air-flow sensors, and the like can be used.

Surface temperature must not exceed X degrees. It can exceed this by Y degrees if the appropriate warning sticker is attached. The sticker must meet standards and they can be ordered for a dollar or two.

EMC: A proper line filter is probably needed. This is a $20 off-the-shelf part. I'm a NARTE Certified EMC consultant and can give you a few hours of free consulting. My specialty is the design of Military EMC Filters.







« Last Edit: October 16, 2013, 08:19:03 AM by WX7G » Logged
W1QJ
Member

Posts: 2990




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« Reply #34 on: October 16, 2013, 12:54:55 PM »

I typically do not see CE or UL stickers on most ham amplifiers.  Some may have them but not sure most have these stickers, and I assume if they did, they would have met the criteria you spoke about.  I am wondering if only certain types of appliances require all that certification you speak about.  You have to admit an amplifier is no different than any other item that comes with a line cord plug that goes into a wall socket.  I don't see any CE or UL listing on Ameritron amps that I can see. 
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AA4PB
Member

Posts: 15067




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« Reply #35 on: October 16, 2013, 01:33:43 PM »

I don't think UL certification is required in the U.S. except for devices that fall under OSHA requirements for worker safety. Your local electrical code may require some permanently installed parts of your home's electrical system to be UL certified. Consumer appliances are often voluntarily UL certified in order to improve their desirability.
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Bob  AA4PB
Garrisonville, VA
KH6AQ
Member

Posts: 8008




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« Reply #36 on: October 16, 2013, 02:08:29 PM »

The Ameritron amps shipped to Europe have the CE Mark.

In the US there are other NRTL (Nationally Recognized Testing Laboratory) besides UL. I have a space heater that has the ETL Mark but not UL Mark.

I read different things about whether a product sold in the U.S. needs to be tested at an NRTL or not. But it's my understanding that whether marked or not it needs to be compliant to the applicable safety standard. When a product doesn't fall neatly into any particular standard the NRTL can choose one or more standards. I see UL60950 chosen for things that are not "information technology equipment." I have used UL60950 and also the lab equipment safety standard (I forget the UL number) and to me they seemed to be quite similar.

The bottom line seems to be that any single fault can occur and the result cannot harm anyone.

I just looked at ten AC operated appliances in the house and seven have the UL Mark, one has the ETL Mark, and two have nothing. The two that have nothing are an Astron power supply and a $99 Chinese tube audio amp.

For tube amps the UL60950 standard seems reasonable. The electrical safety part can drive the AC primary circuitry design and perhaps screws and connectors subject to the 30 amp ground bond test.

The fire safety part of UL60950 can drive the placement of combustible components and the location of cooling holes (they don't want flaming bits to get out of the enclosure). And printed circuit boards need to be "self extinguishing." They need to be marked 94V0 to denote this. I understand that is how G10 PCB material became FR-4, FR for Fire Retardant.

An example of fire testing is that at Tektronix we would do the stalled rotor test on cooling fans. We would also block the fan inlet but leave the fan running. The power transformer winding temperature was monitored (by the change of resistance method) and had to not exceed X degrees after it stablized, sometimes hours later. A temperature sensing device can be used to shut things down if I'm reading UL60950 right each and every unit needs this feature tested.

Then there's the "UL Finger" test where a mechanical finger is poked around to see if it gets chopped off in a moving part or if it can reach into an electrical area.

http://www.ergonomicsusa.com/product/ul-standard-articulated-finger-probe/





« Last Edit: October 16, 2013, 02:12:06 PM by WX7G » Logged
N4OI
Member

Posts: 401




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« Reply #37 on: October 16, 2013, 06:52:51 PM »

I typically do not see CE or UL stickers on most ham amplifiers.  Some may have them but not sure most have these stickers, and I assume if they did, they would have met the criteria you spoke about.  I am wondering if only certain types of appliances require all that certification you speak about.  You have to admit an amplifier is no different than any other item that comes with a line cord plug that goes into a wall socket.  I don't see any CE or UL listing on Ameritron amps that I can see. 

I have heard that hams have become appliance operators -- now we are demanding to be "certified" appliance operators!  I think I am going to plug a couple of bare wires in the wall and practice making sparks.... maybe shock the cat....  (scratch that)....

73
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G3RZP
Member

Posts: 1327




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« Reply #38 on: October 17, 2013, 01:51:56 AM »

WX7G

Is UL60950 the transposition into US National Standards of IEC60950 which would also be transposed to EN60950 in Europe? Sounds a bit like it.

Applying the CE mark to an equipment means it meets all applicable standards - in the case of an amplifier,  that means the requirements of the Radio and Telecommunications Terminals Equipment Directive (which inherently requires compliance to Electro Magnetic Compatibility Directive) and the Low Voltage Directive. In theory, failure to meet the requirements but applying the CE mark and selling the equipment could get you a fine of up to about $7500 and 6 months in prison. However, in practice, at least in the UK, enforcement is zero!

So Ameritron amps sold here should meet the safety requirements. However, if voltages above 50 volts require a tool such as a screwdriver to access them, that is considered a suitable safety measure, so there is an argument that even with this fault, the equipment still meets legal  requirements.
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KH6AQ
Member

Posts: 8008




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« Reply #39 on: October 17, 2013, 07:53:45 AM »

G3RZP, it

UL60950-1, page 101 describes Safety Interlocks. Quoting page 101:

"SAFETY INTERLOCKS shall be provided where OPERATOR access involves areas normally presenting
hazards in the meaning of this standard."

What is the definition of OPERATOR access?

"1.2.7.1 OPERATOR ACCESS AREA: An area to which, under normal operating conditions, one of the
following applies:
– access can be gained without the use of a TOOL;
– the means of access is deliberately provided to the OPERATOR;
– the OPERATOR is instructed to enter regardless of whether or not a TOOL is needed to
gain access."

The UL60950 sentence "the OPERATOR is instructed to enter regardless of whether or not a TOOL is needed to
gain access" is invoked by four sections of the the Ameritron AL-82 Operator Manual:

The SAFETY INTERLOCK section describes the procedure for the operator to access the HV area.

The PERIODIC MAINTENANCE section instructs the operator to access the HV section every 90 days.

The TRANSFORMER INSTALLATION, TUBE INSTALLATION also instruct the operator to access the HV section.


It looks like IEC 62368-1 is to replace IEC 60950 and IEC 60065.

http://www.ul.com/global/documents/offerings/industries/hightech/resources/general/hbse_brochure_final.pdf

http://electronicdesign.com/test-amp-measurement/abcs-iec-62368-1-emerging-safety-standard
« Last Edit: October 17, 2013, 08:02:56 AM by WX7G » Logged
N3QE
Member

Posts: 5598




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« Reply #40 on: October 17, 2013, 08:14:04 AM »

The SAFETY INTERLOCK section describes the procedure for the operator to access the HV area.

The PERIODIC MAINTENANCE section instructs the operator to access the HV section every 90 days.

The TRANSFORMER INSTALLATION, TUBE INSTALLATION also instruct the operator to access the HV section.

And in each and every one of the above cases, the manual also tells you to unplug the amp, and observe HV decay to zero on the panel meter, only then to remove the cover, and gives explicit directions to short out the HV to ground while doing any work. To me the instructions seem well written and to address the corner cases of interlock wrong-side failures, bad resistors in meter divider, non-functional bleeder resistors, and electrolytic soakage.
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KH6AQ
Member

Posts: 8008




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« Reply #41 on: October 17, 2013, 04:32:56 PM »

I looked through UL 60950 again and a warning in the instruction manual does not remove the requirement for a safety interlock. However, having both a warning in the instruction manual and a warning sticker on the unit can remove this requirement if the following is the case (quoting from U 60950)"

   "Where it is not possible to comply fully with the above access requirements and also allow the equipment to function as
   intended
."

A HV safety interlock on an RF amp doesn't meet this requirement because it does allow the equipment to function as intended.
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G3RZP
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Posts: 1327




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« Reply #42 on: October 18, 2013, 02:18:22 AM »

But don't you need a tool ( a screwdriver) to get this access?
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KH6AQ
Member

Posts: 8008




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« Reply #43 on: October 18, 2013, 06:44:01 AM »

A screwdriver is needed to access the HV area. Under UL 60950, 1.2.7.1 only one of three conditions is needed to invoke the Safety Interlock requirement. This condition applies: "the OPERATOR is instructed to enter regardless of whether or not a TOOL is needed to
gain access."

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V47JA
Member

Posts: 205




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« Reply #44 on: October 21, 2013, 05:04:07 AM »

OK, I contacted Ameritron and had several email exchanges with MIKE.  He says they were aware of the problem and thanked me for bringing it to his attention.  He did not say when, but he did say that they are now making the fix so this voltage is not present. ........

If Ameritron was "aware of the problem", why did they do nothing to FIX or notify the Amateur community of the potentially lethal problem. Also, it has now been almost two weeks, since W1QJ found the problem (that they were "aware of"), and still not a word of the problem, or a fix from Ameritron.

73,

John  W5JON  -  V47JA

« Last Edit: October 21, 2013, 05:15:22 AM by V47JA » Logged
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