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Increased fire safety requirements for fuseholders

Impacts of the change in the IEC/EN 60127-6 standard
The fuseholder standard IEC/EN 60127-6 has been revised to improve fire safety.
Effective in October 2017, manufacturers of fuseholders will only be permitted to market products that have been tested and authorized in accordance with the updated standard.

Fuse-holders are suitable for the use of fuse links in electrical and electronic appliances.
They are an essential safety-related part of the appliance protection.
Manufacturers of electrical appliances must comply with the relevant standards and regulations (Europe: the fuseholder standard IEC/EN 60127-6, USA/Canada UL 4248-1 and the household
appliance standard IEC/EN 60335-1).

Besides the fuseholders, IEC appliance inlets and power entry modules with and without EMC
filters are also affected if they have a fuse drawer.

New standard improves fire safety
The first edition of the IEC standard (04/1994) focused on contact protection.
Little attention was paid to fire safety.

Therefore, unsupervised appliances such as coffee machines, dryers or high-speed heaters repeatedly caused fires.
These were caused current overloads (glowing parts), defective parts, faulty electrical connections or electrical arcs when switching contacts.

This project under the sun  :) 
The long story in sort, we have here a six years old (used) DMM4050, this is in perfect shape and retaining it calibration since Jan 2013 which this was manufactured.
This instrument was purchased Feb 2019 from Italy and this is now a Greek resident.

What was obvious after total internal and external inspection, this was that while this multimeter lived in to a distilled environment (active dust filters in the lab), the VFD glass this has premature aging issues, severe burning s that it is hard to be explained.

While I did come in communication with Noritake Itron and I did have now a very reasonable quotation for a new VFD glass, I was also wanted to further investigate and discover the all truth about the source of the problem.

The problem here is Tektronix it self.
Their re-branded 8846A it also differentiates from a Fluke 8846A in the regard of a much darker VFD filter (face plate) which this forces the end user to boost brightness from lowest setting at medium or highest.

Japanese Noritake Itron it is very clear regarding specifications’, their specific VFD has life expectancy of 20 years when this is not misused.

I did mention this situation and problem at TEK Europe and at Fluke headquarters, TEK ignored me and never answered in my two attempts at establishing communication.

Personally I never run out of options, I am used to reinvent the wheel when a manufacturer this is dead regarding spare parts support.
My extended conversation with Noritake-Itron applications engineer this helped me to start looking for alternative materials which they can be used as Filter. 

For the new filter I was able to find locally 2.3mm Plexiglas at correct transparency and tint.
My second key to success this was leftover stripes of self-adhesive film for windows shade (Car accessories).
I did install such film stripes at the sides only of my new Plexiglas window.
Third ingredient this is having a Kiriakos in the room, so him to do the job by not making a single mistake.

The rest of this story it is explained by the pictures below.
Today I do feel extremely proud of my self because my DIY wile this is not risk-free (adding screws), the end result this very satisfactory, and now I am enjoying 40% (at least) of a higher brightness in this Dot-Matrix VFD at lowest brightness setting.
I had never Debranding a DMM before, but I also never had to deal before with TEK customer support either.
By using a third party data loggers software I did succeed gaining more understanding regarding Histogram analysis.

Basically, Histogram at 8846A and of all it brothers, this seems as a toy because it is missing the information of measuring range per its Column.
Due my own testing, I am now aware of minimum measuring range that such a Column can have.

This DMM it has true resolution of 8 1/2 digits,  at Histogram mode,  measured values are limited to 6 1/2 digits resolution, but these Columns it does include 8 1/2 resolution information, and also Standard Deviation measurement this is the only open window so to review 8 1/2 digits resolution of this DMM.

HISTO - GRAM  this is a GREEK definition ( HISTORY + GRAMI ) = ( History + straight line)  = History recorded by straight lines.

It is possible these two pictures bellow to help your understanding, a little more, if you see a Histogram this be rotated at it Time Axis.

In a ideal world, it is possible a voltage reference to demonstrate just a 1uV of fluctuation within 500 taken samples, in such a scenario Histogram will present a single Column
Handheld multimeter / Re: Fluke 28II battery compartment
« Last post by Kiriakos GR on March 20, 2019, 11:01:20 PM »
I just mentioned few hypothetical scenarios as precautions that every one should have in mind about 28II and similar.

You better check also calibration manual for 28II, this is more informative than the User Guide about battery compartment assembly.
Also be aware that O-ring they do have limited life cycle, no more than four years.

I did sold my 28II this year, this stayed nine years in my hands totally undamaged, since day one and when ever I did battery replacement, I was adding Vaseline over the O-ring so to protect them and to prolong their life.
Battery cover installation this is not easy, this must be installed with care, be centered and screws must be tighten slowly and equally, correct way this is tighten gently one screw after the other at circular path.

Handheld multimeter / Re: Fluke 28II battery compartment
« Last post by Marco1971 on March 20, 2019, 10:07:16 PM »
Hi Kiriakos, in my case i made carefully reassembly with little very little force and obviously through Torx T8 screwdriver.
In the italian version of Fluke 28II user manual https://dam-assets.fluke.com/s3fs-public/2x_2____umita0100.pdf on page 40 there's mention for Philips screws.
Not oversized cells but Energizer Lithium Ultimate in the same form factor AA LR6 E91


Handheld multimeter / Re: Fluke 28II battery compartment
« Last post by Kiriakos GR on March 20, 2019, 06:48:33 PM »
Well as far I remember, Fluke User Guide this is very clear regarding instructions,  assembly of battery compartment cover this requiring special Torque Screwdriver.

Unorthodox use of force over these TORX screws, it can naturally deform this plastic cover.
Any one not using correct in diameter batteries it is like asking for trouble. 

If you do all three mistakes it will get damaged,  the third mistake is to leave it exposed in the sun light in the summer, when there is inside oversize cells, and all TORX screws tightened with brutal force. 

Handheld multimeter / Fluke 28II battery compartment
« Last post by Marco1971 on March 20, 2019, 10:33:22 AM »
Hi, after changing batteries in my new Fluke 28II (made in USA in September 2018) from Energizer Alkaline to Energizer Lithium Ultimate i discovered the same problem reported here (2012)


Same bulging in battery compartment after closed it with six TORX T8 screws.

Then i wrote to Fluke European support (for Italy at this address roc.italy@fluke.com) asking about this "problem".

Using tools of the enemy so you to explore your own DMM, this increases further the FUN Factor  ;D ;D
This message aiming mostly software developers target group.

The information below this is shared notes of a Chinese person which did some experiments with Lab-View before nine years ago.
Tektronix DMM4050 Programming Experience

Tektronix DMM4050 programming, use experience
Refer to the DMM4040 and DMM4050 Digital Multimeter Programmer Manual for
details .
The simple acquisition procedure is described in the document " Optimization
System Speed for I/O Operation " ( page 6 ).
########################### #####################
*cls # This clears all error prior to initiating readings
Conf:volt:dc 0.1 # Set the DC range to manual and 100 mV.
Volt:dc:nplc 0.02 # Set the NPLC to faster reading rate 4 1/2 digits.
Zero:auto 0 # Turn Autozero off.
Trig:sour imm # Set immediate trigger.
Trig:del 0 # Set trigger delay to zero.
Trig:coun 1 # Set trigger count to one or specify a larger number.
Disoff off # Turn display off. This may slightly improve reading rate.
Syst:rem # Put the DMM4050 in remote. Only needed for RS-232 or Ethernet
#(required for READ? or MEAS?)
Samp:coun 100 # Set the sample count from 1 to 5000.

:INIT; *OPC? returns 1 indicating that the measurements have been taken and are ready to be transferred to the computer by using the :FETCH? command.

The network interface of the DMM4050 does not support automatic TX/RX polarity conversion.
Pay attention to the connection mode of the network cable.

Entire PDF with more details about this MAESURE.VI project it is available to download below. 
The document it is translated from Chinese to English due web translation, beware for syntax errors.   
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