ITTSB.EU Blog Forum
Electrical Test and Measurement instruments => Bench-top multimeter => Topic started by: Kiriakos GR on October 13, 2020, 06:12:05 PM
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Do you think that your 8845A / 8846A this gets warm more than what you will expect at standby?
I will start with one example, at my workshop in the hart of summer I had an almost constant of 30 Celsius indoor.
The DMM top cover this had a constant hot spot of 42 Celsius.
The DMM was configured by the adjusting plate at the back, for operation at 220V input.
Today I did some power consumption tests.
By doing so I did switch the power meter in Volts, and it read 237V AC.
This motivated me so to configure the 8846A at 240V AC Input.
In my surprise the power consumption this now become less by almost 1,5W.
220V configuration and stand by this was 11W
240V configuration and stand by this is now 9.5W
240V STATS
DC range at 1000V = 13.2W
AC range at 1000V = 13.4W
Ohms range 10 Ohm manual = 14.0W
FREQ-PERIOD = 13.2W
DMM REBOOT = 14.5W (Highest).
I am not aware of how 1,5W less this will influence 8846A internal temperature, but at least you all have now statistics for your own comparisons.
Hints:
My display brightness intensity this is set to LOW.
If you use a low cost power meter then accept 3% -/+ Error
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Any temperature case cover statistics after the new change ?
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Any temperature case cover statistics after the new change ?
While it is too soon about of me obtaining a complete picture, I have data from 24C room temperature.
I did place a wireless temperature sensor on top of 8846A (transformer area) last night.
And this morning, I did add and one K type thermocouple.
At 24C room the 8846A this is now at 28C.
The multimeter with the K type thermocouple, this is my first ever and this is now 35 years old. 8)
I do trust the temperature range but it missing a rich digits resolution.
Even so, four degrees above room temperature this is the NEW fact so far.
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I am suspecting that Mains input voltage 220 VS 240 ACV, this will influence mostly the temperature of the pile of 8846A DC voltage regulators.
With 235V input voltage at 220V input setting, the transformer this will deliver a bit higher ac voltages, and all voltage regulators they will dissipate more heat.
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I think that after of me monitoring the new setting for almost 14 days I can now deliver good standing statistics.
And @overvolt he is very close to what is happening.
All 8846A DC voltage regulators they run much cooler.
8846A mains transformer this runs cooler too.
The DMM does not get warmer that 5~6.5 Celsius VS room temperature, at stand-by and neither this gets any warmer even with the display active.
So the first fact, this is that display luminosity circuit this does not contribute to DMM inner case temperature.
The Mains power-line this feeding all my bench instruments this is guarded due UPS APC SMC1500I (1500VA) and so there is no fear for Mains failure.
Now I have one after thought but this needs to be confirmed, now that the 8846A this running with proper mains feed, I am close to assume that it factory calibration this has recover at a better point.
But such confirmation this is difficult, the difference this should be a few ppm.
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Two days before New year 2026, and I started running verification tests at my 8846A. ;D
Within 2025, my significant investment this was getting a real single phase power meter.
And I totally forgot to perform a fresher power consumption AC Mains test at my 8846A.
PM9913 this is specialized AC power meter for measurements of very low AC power.
As it is demonstrated bellow, I did run two quick tests, 8846A soft power On and OFF.
The measured differences in Watts Power, these now clearly looking at much higher precision than the old test.
New test at 16C room temperature, and 12.40W this my latest and accurate measurement.
The low cost power meter 10A range, this had measure 13.2W = 0.8 Watt higher.
At soft Power OFF mode, the new accurate value this is 9.168W , while previously I had measure stand by at 9.5W, = 0.33Watt Error. :)
I have learned allot in the year 2025, about AC power measurements, and the reason of why the inexpensive power meter shown small error, this is the copper transformer within the 8846A.
The copper transformer elevates the Power Factor at a point were the low cost power meter, this can measure with minimal error.
The test results they would be much more different, if 8846A this was using a switching power supply instead. ;)
The measurement of Low Power Factor, this is not possible due 10$ worth power meter.
PM9913 this is also capable to display VA and VAR, at this test, I selected VA.
PM9913 this is also able to perform averaging due PC software, but I do not think that FLUKE Corporation this is interested for a complete Power consumption printed report according to IEC. ;D
In round numbers, 12.40W = 16.18VA at 235V Input.
I did not use stabilized input voltage ACV, but I got lucky, both high and Low watt measurements they were captured at identical conditions.
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Just spotted another Greek patent, crystal clear add-on over the communication box 8)
180 degree visibility of communication activity LED's !!
This is an extremely smart thought. ;)
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Just spotted another Greek patent, crystal clear add-on over the communication box 8)
180 degree visibility of communication activity LED's !!
This is an extremely smart thought. ;)
24H before the new year 2026, I did become extremely creative. ;)
I did rebuild even the rack that I keep my instruments stacked.
Now everything at my work-bench, this is positioned at best possible way.