Electrical test and measurement equipment reviews.
ITTSB Blog
BRYMEN BM257 Review – By the eye of the Industrial electrician.
By Kiriakos Triantafillou July 12 © 2013
Part – 5 Just another one multimeter with Industrial profile?
Part – 6 LCD display – Range switch
Part – 7 Case / holster – Safety /Fuses
By having one very positive impression by the BRYMEN BM869 multimeter which is a full size professional model, I wanted to discover too and the best BRYMEN offering at medium to small dimensions.
By reading the specifications of their fresh BM257 my curiosity level jumped up, and my invitation send to BRYMEN right away.
The BRYMEN BM257 it can be easily described as compact Swish Army Knife in the range of the latest marketed multimeter's in the middle of 2013.
It comes loaded with new features never seen before in such small footprint of meters.
What is the most interesting is the fact that even by been loaded with the extra features it is still easy to use and friendly.
The small revolution in this fresh design of BRYMEN is AutoCheckTM feature which automatically selects measurement function of DCV, ACV or Resistance (W) based on the input via the test leads, plus with Z-Low and all those functions are hosted in a single position of the range switch.
Electric Field EF-Detection is another welcome addition plus the meter it is fast with easy to read 6000 counts display with a very well designed back light.
The BM257 multimeter is well build and looks great but it does hide few annoyances, some of them spoil the fun to electricians’ but the issues are very minor regarding importance.
About using it in electronics its not the best idea due it official bandwidth limits, voltage measurements with high accuracy in the acoustic band from 4 kHz up to 16 KHz are not possible.
The BM257 is also capable for Data logging by the use of BRYMEN Data logging Kit (IR-USB cable & software) which comes as optional.
I do feel very excited about this meter.
Those fresh additions on the product design of multimeter's it is a proof of new waves of change, which came so to set new standards of what called today as modern multimeter for industrial electricians.
The old-fashion rule of the thump about been able to evaluate the general picture of a multimeter by how it looks externally, it does not stand any more as judgment factor.
Part – 2 Introduction with the BM250 Series.
BRYMEN deigned the BM257 to be the most features rich model of BM250 series which includes four meters.
The brother model to BM257 (True RMS), is the average measuring BM255.
The other two brothers BM252 & BM251 are both high quality meters with a striped down features set, which translates to a lower pricing too.
Hobbyist in electronics and cars electricians will greatly appreciate them.
In those BM252 & BM251 their only difference is that the BM251 lacking capacitance and temperature modes.
The BM257 comes well packaged and includes the user manual, K-Type temperature sensor & high quality test leads.
Regarding the test leads BRYMEN send to my mailbag by accident their 2mm exposed tips (silicone) test leads.
Even so they did informed me that every buyer in Europe will get the new test leads set with protective covers, the exact item which came with the BM869.
Part – 3 Exploring the basic features
After writing six reviews about truly well made meters in the last 12 months I did came in the conclusion that I need to change some thinks in my reviewing style.
Therefore the basic features section in my reviews will be more Spartan in the count of words.
Continuity mode
Lightning fast response & clear beep sounds with no scratching, and
is even a bit faster than BM869.
This BM257 has a latched beeper and by been so extremely fast for such a small size meter it will gain many positive votes from the side of the demanding users.
Ohms range
The BM257 is a 6,000 counts meter with an sampling speed of 4,5 times per second.
What it does worth to be note is that from values of 1 Ohm and up to the last range of 60M Ohm, the meter looks and is very fast.
At below the 1 Ohm values I have the feeling that slows down a bit, but even if this detail it is there, it is not an issue when it comes down to measurements.
The specifications of the lowest range are 0-600 Ohm, which is good enough for electrical work and components testing.
Relative mode
The relative mode does not lock the auto-range.
I was able to REL-Out at zero ohms
and go up to 10M Ohm.
Impressive!
Bar graph – speed comparison
I did this comparison directly with the bigger brother BM869 as both meters claim equal sampling speed my own thought was that I should expect the same behavior from them.
In a way yes, both are very close, truly close, the BM257 it did shown their straight when worked in their 6,000 counts display resolution at the 6V range.
The performance of Bar graph in this range is amazingly fast, by getting in higher volt ranges you get the feeling that Bar graph is not that fast, but this is one illusion.
The variable analogue knob on those professional power supplies is unable to create a true simulation of true rapidly changing voltages.
Capacitance meter
I am not aware what BRYMEN did here but this BM257 is 300% faster in every measurement in comparison with BM869.
It needed one second to measure a 40 uF (start motor capacitor).
And needed a bit more time to measure a 2200 uF electrolytic but even so it did the job three times faster than it big brother.
DC / AC volts
I have start having the feeling that I will never see one not properly calibrated BRYMEN meter when it comes down to DC voltage ranges.
I did all sort of tests and I did not find anything wrong to it.
On AC volts dedicated range the MB257 comes with specifications of 50Hz – 500Hz as bandwidth, in my tests it performed even higher up to 3-4 KHz (3 KHz sine & 4 KHz square waves) above those frequencies the meter is not possible to hold it accuracy.
Basically about the bandwidth there is no complains specially if we think that is a small sized and True RMS meter for electricians.
If you work exclusively with electronics and you seek for a low priced DMM but modern and safe the BM257 it can come close to your needs but it is not a BM869 regarding high bandwidth.
The brother model BM255 as average reading meter, by design it must have much less bandwidth in comparison to BM257.
But there are some applications even today which require an average reading meter.
I did have recently one conversation with one Japanese engineer which he told me that prior the existence of VFD filters on DMM, they did use average measuring meter as alternative way for measuring volts in Variable Frequency Drives (motors) measurements.
The idea behind this suggestion is about using the low bandwidth multimeter against the unwanted interference at 400Hz and above instead using an active Low-pass filter.
But such a measurement it is impossible to have sufficient accuracy, even so it does stand as practical way so one experienced electrician to get some information or indication of what is happening.
AC Current accuracy in mA range
The BM257 has a very friendly size which young electricians or students will find as attractive too.
Therefore I made one simple test by using a 75W light bulb and set in series three full scale multimeter's with it.
Regarding accuracy the BM257 found spot on with all the other meters in the AC/mA range which is great news.
Naturally in such measurements it is best to start with the 10 Ampere range, as reinsurance that your load even in the range of mA is not high enough to blow the Fuse of the meter.
As known the Mains voltage is not totally stable, but I got lucky and managed to get some numbers and pictures in a time which was acceptably stable.
With a load of just 318 mA you do not expect maximum accuracy in the 10A range, even so I will present measurements of both ranges just for your information.
Model:_______ 10A & 600 mA range
BM257_______ 322 mA / 318.1
BM869_______ 316 mA / 318.1
Fluke 28II ____ 320 mA / 318.2
Agilent U1272A 319 mA /317.8
The numbers speak by them self’s regarding the quality of the meter, but they say too that my 75W light bulb, is not any more in a great shape.
The testing in the mA range indicates too that the current shunt in this meter works great, therefore there no need to collect numbers about the 10A range by using a higher current load.
DC-mA test & sampling speed.
It happens to own one great test bed which is actually one NiMH advanced charger which has one special mode called as “refresh mode” which is activated prior getting charging the battery by the use of pulses.
What it does is to send to the battery one positive strong pulse and one negative in polarity pulse rapidly and repeatable.
Its pulse last for 500 ms and so we have two of them in one second of time.
Now you may guess that only true fast meters with high sampling rate, of four times per second or more, can even display the measurement on their display, and also give an almost accurate measurement too.
The expected behaviour of a meter under this stress is to display on screen for one second the positive value and for another one second of time the negative current value.
Those fast and constant reversed pulses causing one positive current flow of 800mA and one negative up to -500mA in to a NiMH battery.
This “refresh mode” works for 5 minutes prior its and every charge cycle.
The BM257 it did passed the test, but it succeeded it with a bit of difficulty in the standard measuring mode regarding accuracy.
By activating the Min/Max mode the BM257 it started to fly high regarding display update rate and even by been more accurate.
Usually the Min/Max mode raise up the sampling to 250 ms and it is expected to do a better job on such type of demanding measurements.
Now you may guess that a slow multimeter, with out even Min/Max mode on it, it is impossible to pass from my test bed, and I do run this test to any meter which arrives for a product review.
Temperature measurement
BM257 standing next to BM869 with identical (BRYMEN K-Type probes),
One glass with cold water in the middle, and both meters needed 3 seconds to measure those 14C when touched the water (room temperature 21C).
I do feel very impressed about the amount of advanced features which BRYMEN managed to include in their smallest professional grade meter.
Let’s count them for start.
1) AutoCheckTM with Z-Low
2) Crest measurement
3) REC = Min / Max
4) Frequency measurement
5) Electrical Field Sensor / Non contact probe
6) Data logging
AutoCheckTM with Z-Low
What we have here is one single range switch position in the meter which is capable for automatic selection by the meter of the range and type of measurement.
AutoCheckTM as technology is a very fresh concept (middle of 2012).
This new technological concept it is not widely spread yet, but BRYMEN adopted it and now I have the chance to review it.
This Smart called circuitry is capable to detect AC & DC Volts plus resistance, and to properly setup it self with the correct settings so the meter to display the result of the measurement.
Additionally all the secondary functions (Frequency, Min /Max, Display Hold) can be used with it.
Generally speaking what we have here is one multimeter with two build in gear boxes and I will use in my example the gearbox of a car, which the driver can switch between Auto & Manual at any time.
The drawback in such fully automated circuits is that they need some extra time to respond and measure.
On the other hand this new feature could possibly win the heart of people who expect one multimeter that is extremely easy to use and safe too by this foolproof design.
In order to find how slow the auto gear box can be, I got in my hands a chronometer.
I did two basic measurements which I did repeat about five times it’s one so to gather reliable numbers.
Note: The meter test leads connected to mains all the time by an electric extension socket with power On/Off switch.
Test No1: Boot up time and measurement with ACV vs AutoCheckTM
ACV = 3 seconds & AutoCheckTM = 4 seconds
Note: Multimeter powered up & ready to measure.
Test No2: Measurement time delay, ACV vs AutoCheckTM
ACV = 1 second & AutoCheckTM = 1 second
By discovering that BRYMEN managed to implement the Smart Meter concept or better said technology in their meter with such fantastic results, I think that I am forced to reevaluate even my own first impressions of what to expect by this new innovation regarding speed.
It is fast enough so to not considered as slow and unproductive functionality when compared with the dedicated range for volts measurements, and so BRYMEN deserves one thump-up for this well made implementation.
Z-Low is another additional feature combined with AutoCheckTM regarding volt measurements, as known all that it does is about adding one small load on the pair of cables, by this we can become aware if there is a true volts source behind those cables or not.
Z-Low up to date was a dedicated functionality serving exclusively the AC Voltage range of a multimeter.
But with the BM257 which comes ready for AC&DC measurements from the same range switch position, the Z-Low effects things differently.
Regarding AC 220V Mains and Z-Low, the BM257 load the line with 5mA, which is the highest load seen in a meter from anything reviewed so far.
Z-Low at DC range it is a very new experience even for me.
I did some measurements and collected data about how the load is changing regarding the volt input.
Volt / mA Load
3V _ 0.5 mA
6V _ 2 mA
12V _ 5.62 mA
15V _ 7.3 mA
24V _ 12.4 mA
37V _ 18.3 mA
I have no comments to make about this behaviour of the meter regarding how helping it can be proven in DC volt measurements.
Either way my job is to inform you about what to expect, and this is what I do.
AutoCheckTM ACV Bandwidth & frequency range.
The word of BRYMEN about ACV bandwidth is that the specific range is designed exclusively for 50/60Hz line frequency and by design it offers it highest accuracy.
My finding is that the meter is more generous than that and goes up to 500Hz.
Frequency range / Hz mode,
The Users manual it did confused me with one table of data which is exclusively related to minimum input voltage (trigger voltage or current) for an accurate frequency measurement.
The given specifications are up to 50 KHz with 0.03%+3d
For electrical work the sensitivity of it as frequency counter is very acceptable.
Crest measurement / ACV range
Here I did spotted that the meter have a small issue and gives a measurement of few volts less than the BM869.
ACV input stable to 225 volts.
BM869 / +315.5 & -315.8
BM257 / +311.9 & -311.7
Min-Max ACV range
As I discovered also in the current measurements the BM257 becomes fast as rocket in Mix/Max mode, the Average reading it is missing from it, but even so this multimeter it is a fast performer and equal to BM869.
I did tested them both against its other, by having them measuring 225V mains simultaneously in a duration of 60 seconds.
Both multimeter's captured the same peak voltage value in their significant digits.
BM257 = 226.6
BM869 = 226.11
Electrical Field Sensor / Non contact probe
To be honest I do not have much of experience regarding the latest electrical field sensors.
Even so I do own one electrical field sensors from a German brand, it was made around 1995 and my tool is mostly for live cables detection prior drilling a wall.
It haves a flat surface (pad) outside and also from the inner side there is a small flat coil and some electronics about activating one LED and a Beeper.
The sensitivity it gets adjusted by an analog potentiometer.
The BM257 comes with a modern EF Sensor and circuitry, which has acceptable sensitivity (non - contact mode) and even comes with auto ranging.
The measurement is shown in the screen as mini separate bars which the amount of those bars (bar graph indicator) represents specific detected voltages.
20V = 1 Bar
55V = 2
110V = 3
220V = 4
440V or more = 5
The BM257 EF detection sensor is located at the top right corner of the meter and actually 1 centimeter away of the curve.
About EF detection in Non-contact mode I will say that I did not get impressed.
For getting a realistic indication the meter must actually touch the insulation of the live cable.
The spotted annoyance is the fact that the 4 bars indication is show in both voltages as 220V and 380V.
BRYMEN designed the EF detection to cooperate also with the test leads.
Just one test lead touching bare copper it would work as another EF antenna, and the meter will detect and display EF of a single phase line.
Regarding the fact that EF cannot detect the difference of 220V & 380V, after some thought, I did realize that EF is all about triggering and not a measurement.
From one triggering point to the next it is required the double amount of energy.
Even my UNI-T UT15C volt stick it works by the same way in the wired EF mode which is presented by LED, my choice about getting it was due the additional LCD volt meter and naturally about the phase rotation indicators.
Data logging
The BRYMEN KIT Model: BRUA-20X is what you need so the BM257 to show it value in data logging.
The KIT comes with two main parts, the BUA-2303 (USB to Serial converter) and also the BC20X cable with serial connection from the one end and the infrared module in the other.
The infrared module is designed very well and it does securely attach in the back side of the multimeter case.
It can be used with the holster on the meter and also with out it.
Regarding the serial connector on this BC20X cable it comes with regular locking screws so to be attached securely on the BUA-2303.
In my sample the screws found to be very sort for this task and they can not even touch the metallic nut in the other end.
I did inform the company and they did all the necessary actions.
The KIT comes also with the software CD, which includes Driver & Help file and naturally
the Bs25x Data Logging System Ver 5.0.0.2.
I did run in to problems when tried to setup the meter and the software but let’s see them in detail.
In order to activate the infrared port on the multimeter, you need to press the Hold button and to power up the meter.
After doing that the port becomes active but not the icon in the BM257 display?
I was expecting to see the icon active as reinsurance that the port is active.
The next inconvenience is that the software does not have COM port / Auto-detection.
You need to check your PC configuration (Windows system) and adjust the Port settings manually in the software, before you press the Link-up button.
Basically I do highly recommend reading the entire Help file (CD Disc) prior trying to hook cables and later on trying finding solutions by using common guesswork.
The Bs25x Data Logging System belongs among the acceptable software solutions for data logging, but it does not win a top prize and BRYMEN is aware of it.
In the positive side of things is that the software other than writing the log it displays the Max & Min values constantly in special separate windows.
And when logging you can see easily if there is any unexpected reading, which will trigger your interest so to search further in the log file so to discover more details about the event.
What I was unable to do with the software was to set my personal Min/Max parameters regarding voltage input in the graph window, so to have in the screen one more high resolution graph which will contain voltage readings between 210V to 230V.
Instead of that the software auto detects the max values and adjust the range by displaying even in ACV mode 250V as Positive / zero / - 250V.
All those unwanted information’s takes away usable resolution from the graph window and the actual graph line looks poor regarding variations.
Naturally by exporting the data to CSV file, you may use the power of your spreadsheet editor about making you final graphs exactly as you like them to be.
The BM257 combined with the data logging software are able to offer one sample per second as fasted sampling.
This sampling speed is good enough to monitor Mains voltage or current when consumption and over time anomalies needs to be detected.
By using a much slower sampling as for example every 1 minute or more, you can make exceptional graphs of a battery under load and their behavior when is discharging.
Another one advantage of the Bs25x Data Logging system, is that you can save and review back every session, by saving the file in one file format that is recognizable only by the specific software.
As for example: filename.g52
By having your session stopped you may export the data also as CSV file so to be imported later on to your spreadsheet editor.
I am aware that all those steps sound as a bit complex to be executed by a totally inexperienced person at using computers, but the life of an electrician is full of new challenges.
Regarding BRYMEN their solution it does work well, but they need to improve the small details which always make the difference.
Part – 5 Just another one multimeter with Industrial profile?
This title is actually a question, which translates that is it enough one good looking meter to aim for the interest of industrial electricians because simply looks robust and it is usually painted as yellow?
Also on the carton box it could have the description as industrial multimeter but the words in our times are easily manipulated by the fellows of marketing and usually they become misleading.
BRYMEN deserves a small prize for been sincere again, regarding their marketing strategy for the BM250 series, they have written on the carton box of it that is a Practical digital multimeter.
This is a simple description, but even so it makes obvious that this product aims making your life easier by offering the promise that in the end you will purchase a friendly meter and a lightweight companion.
By reading the users manual noticed some descriptions regarding NMRR & CMRR which are actually active filters.
I will copy paste the information's as is so read and judge by your self of their usefulness.
NMRR (Normal Mode Rejection Ratio)
NMRR is the DMM's ability to reject unwanted AC noise effect that can cause inaccurate DC measurements. NMRR is typically specified in terms of dB (decibel). This series has a NMRR specification of >60dB at 50 and 60Hz, which means a good ability to reject the effect of AC noise in DC measurements.
CMRR (Common Mode Rejection Ratio)
Common mode voltage is voltage present on both the COM and VOLTAGE input terminals of a DMM, with respect to ground. CMRR is the DMM's ability to reject common mode voltage effect that can cause digit rolling or offset in voltage measurements. This series has a CMRR specifications of >60dB at DC to 60Hz in ACV function; and >100dB at DC, 50 and 60Hz in DCV function.
If neither NMRR nor CMRR specification is specified, a DMM's performance will be uncertain.
Part – 6 LCD display – Range switch
LCD Display
By powering up the meter for first time it did gave me a huge positive impression, the digits has the same shape and dimensions with my first (Made in Taiwan) multimeter which I personally select from the showcase of a local shop at 1988.
In other words the BM257 came with the display which I favor the most even up to date.
One of the primary marketing points of BRYMEN is the easy to read LCD.
And I will totally agree with them, due the fact that they did use the friendliest classic LCD for 6,000 counts meter with a single line of digits.
Regarding the back light the company made the right choice this time and BM257 comes with a friendly bright orange color, which is very successfully implemented especially regarding brightness.
The timer keeps the back light active for 32 seconds.
One small annoyance is still the narrow viewing angles, which causes some ghosting or fading digits if you like to view the screen under angle.
Due the fact that in compact meters we use them by holding them at hand, this annoyance will not look as significant, as it does when we use a meter mostly for bench work.
BRYMEN informed me that it is in their plans to change their LCD supplier.
Range switch
Even if the meter has smaller footprint than BM869 it does have the same range switch in dimensions and feeling.
When reviewed the BM869 the range switch did not satisfy me that much regarding the dimensions.
I do favor the wider ones which you can easily rotate even by wearing gloves.
By using the BM869 for over a year in my bench work, I will say that never felt stressed about using the range switch.
But there is one small annoyance on the BM257 which it is caused by the position of the test leads (banana input) on the face plate.
Those banana inputs in the sides, they are extremely close to the range switch, and the banana plugs of the test leads are forming almost a front wall standing next to this range switch.
And what happened to me was that my fingers they did touched those bananas plugs more that once in my attempt to rotate the range switch when was passing from the ACV range.
Just one centimeter additional clearance it would disappear this true annoyance which takes away some positive points regarding proper design and a true friendly range switch.
Batteries
My first impression after discovering those two tiny AAA was neutral to negative.
But after considering what Agilent did in their U1272A which by using four AAA it did manage to offer accepted duration as battery life, I thought that I will have to wait and not to jump in hurry conclusions.
The meter came with AAA GP Green-Cell (Extra heavy Duty) 24G R03 1.5V and it is good to go up to 2016.
By using the meter for 30 hours in several measurements, plus 2 hours exclusively for data logging, both batteries found to have 60% remaining available power.
By a very rough estimation this meter will not pass the 150 hours mark with similar high quality batteries, and it may drop even to 100 hours with regular batteries.
How all those estimations translate in real life?
My thoughts after testing it are that this meter is not a power hungry design, and even the power saving mode helps allot about minimizing battery consumption.
I did forget it accidentally in sleep mode for about 24 hours, and the next day it waked up with out this event to affect the battery charge level.
This info motivated me to make some extra power consumption measurements.
As you will discover in the photo gallery in the end of this review, the numbers speaks by them self’s.
Normal operation = 3 mA
Back light On = 21 mA
APO (sleep mode) = 1.5uA
Those numbers indicate that BM257 it is a true gem, due the fact that it does make an excellent use of it batteries.
Generally speaking most latest meters comes with very improved specifications regarding battery consumption.
The prices of those power quality analyzers have drop down a bit.
Fresh regulations by the European Union and also the Think Green movement made the electronics designers to pay more attention in such details.
In conclusion regarding power management, when you choose a modern multimeter you get more in the hand (Less money for alkaline cells per year) than just a sparkling looking meter.
Part – 7 Case / holster – Safety /Fuses
Case / Holster
One very high quality plastic case is what surrounds the hart (PCB) of the BM257.
BRYMEN did a great job again, and proved even to me that smaller size it does not translate to them as cutting corners about lowering the cost.
The red add-on rubber holster is also from the same high quality rubber as in the BM869.
It does add to the meter some extra protection against small accidents and also gives a great feeling in the hand regarding perfect grip.
With a BM257 in your hand there is no chance for common accidents as for example the meter to slip away from your hand because of a slippery holster.
Yes it is that good!
At the back of this red rubber holster the design retain it perfect ness, any engraving on it about the test leads or even the special point about hanging the meter from a nail, or even the point to attach the data logging cable, every little detail is well taken cared.
The tilting bail is very small but well made, lets not forget the BM257 is a compact size meter, and I believe that BRYMEN designers team did their best to offer an over all practical design.
By holding the meter in my hands today, I will agree that the result of their work is truly satisfactorily.
Safety / Fuses
By discovering BRYMEN at 2011, I discovered also a very serious company which is actually leading the way regarding the CAT IV 1000V.
The BM257 is a 300V CAT IV / 600V CAT III, those specifications makes obvious that this meter is designed to serve in common electrical troubleshooting which electricians engaging with at 90% of their time, which is far from high energy sources.
About the fuses & battery compartment by unscrewing just one regular cross type screw, you have full access to it.
The fuses do not look easy to extract as they are positioned in one depth that I does not look reasonable to me.
Due this decision of BRYMEN products designers, you will need to use one proper in dimensions screw driver, and with some patience to use it as lever.
More specifically my tip about the 10A is to hold down the left side of it with your finger (current shunt side) and with a 4mm screwdriver to lift the right side of the fuse.
The 630mA fuse it’s the harder one to extract, just use the lever idea and push it at the top or the bottom on it, it will slide slightly but eventually it will lift up.
Part – 8 ITTSB comments over the design & Conclusion
Intro:
In 7 of June ITTSB complete it first year of operation, and I feel very proud for the great cooperation that I have so far with marketing teams from all over the planet.
Self-improvement as reviewer is also one of my targets, and after getting some feedback and comments from my readers, I made the decision my witting style in those reviews to become more lightweight regarding the listing of the technical specifications’ of its product.
That information’s are available and easy to find at the manufacturer product page.
ITTSB is now equipped with a complete set of additional tools which can verify the performance of any multimeter and Oscilloscope.
The BM257 have been tested in depth and my findings become known to BRYMEN even prior this review been posted, so to get their answers too.
I like to thanks BRYMEN and Mr. Gary Wang for his full cooperation, thanks to him and the BRYMEN team I was able to have access to BRYMEN latest products portfolio which is loaded with truly innovating meters.
ITTSB comments over the design
When this moment comes what I do is the sum of all the discovered annoyances.
1) The IR Port activation icon on the LCD does not get active when the port becomes active.
BRYMEN is aware of it and this is their answer: However, as the ROM size and LCD segment number limits of the microprocessor, some trade-off designs need to be made and some minor features or display need to be sacrificed.
2) Crest measurement / ACV range the BM257 measured a bit lower than BM869.
BRYMEN is aware of it and this is their answer: The capture speed is 0.8ms/time for BM869 and is 5ms/time for BM257. The faster speed can get closer reading to the peak value (318V =225x 1.414) of 225V sine.
3) EF detection behavior / accuracy.
EF-detection is a non-contact measurement. Its accuracy can not be that good as contact measurement. That is the reason why EF specs are always with wider tolerance. Other meters having EF in the markets have similar performance. It is the nature of EF.
In summary I will say that my personal findings do not look serious enough so to steal away the shine of BM257 which rightfully deserve due it positive points.
Even me I can be forgiving and stay unaffected from negative thoughts when this meter is offered at a price point close to 130 EUR with taxes, at that price point this meter it is one real bargain.
In the price range of 150 EUR or more my thought is that HIOKI have offerings which they also worth to be considered too.
Conclusion
Well if BRYMEN was have in mind to offer one professional grade multimeter at compact size which will blow away any cheap and slow multimeter, yes they did succeed it.
From my experiences regarding the market of compact size multimeter's I will say that for many years it was in the hands of Shenzhen mainland, and most offerings was slow and poorly implemented.
UNI-T or Mastech or V&A are tragic examples of bad taste regarding design and the most important is that they found to be UNSAFE for professional use.
False printed specifications’ regarding CAT tolerance markings, unsafe fuses and poor PCB manufacturing, plus CE certifications which are printed with out proper inspections, are details which they seen the light as information thanks to the curiosity of young kids.
Which due their passion for bragging rights or about to discover the inner world of their multimeter, they did take them apart and posted pictures of them.
Naturally those kids are incapable to evaluate specifications and judge regarding PCB manufacturing standards, but the trained eye of the elders it can not be fooled.
As professional electrician it makes me feel proud those days the discovery of such BRYMEN products which other than quality they carry with them and the Taiwanese flag which was an old symbol of quality in my region prior getting bombarded by low cost solutions from China mainland.
In the question of how the BM257 compares to other similar in quality solutions,
I would say that currently I have not touch one of those compact size Agilent meters, or the equivalent model of the newly released HIOKI meters.
I am open for suggestions for on-demand reviews under a fee, if those companies are interested for such cooperation.
Regarding technical features and over all performance the BM257 it is a safe bet.
It is modern and fast, accurate and safe, capable of advanced measurements and data logging, acceptable battery consumption plus compact dimensions and lightweight.
Easy to read LCD, with successfully implemented back light which stays active for 33 seconds that is plenty as time for taking an important measurement in dark places.
My last word would be that even as main multimeter, or even as auxiliary selection (for your more compact in size tool box), the BM257 will not feel as sort when using it to troubleshoot even advanced problems at 600V CAT III power circuits.
I like to thanks BRYMEN and their team for the great cooperation with ITTSB up to date.
I do strongly believe that those product reviews they have too elements of education, which help even professional electricians to start appreciating even more of what one good multimeter is capable to offer back to them.
Pictures gallery.
APC Smart UPS 1000 / Battery replacement and electrical inspection, Inverter & Charger.
FLUKE 8050A multimeter, NICD charging circuit damaged, after repaired 98 mA/136 mA (Low/High)
BM257 power consumption measurements by the latest HIOKI DT4282
BM257 AC/mA test 75 Watt 220V lamp as load, all meters in line. (LCD back light comparison)
BM257 & Agilent U1272A LCD back light comparison
BM257 BRUA-20X USB interface Kit BM200/BM250 Series
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