This is only a preview of the April 2016 issue of Silicon Chip. You can view 43 of the 96 pages in the full issue, including the advertisments. For full access, purchase the issue for $10.00 or subscribe for access to the latest issues. Items relevant to "Touch-Screen Boat Computer With GPS":
Items relevant to "Microwave Leakage Detector":
Items relevant to "Fridge/Freezer Alarm":
Items relevant to "Arduino Multifunction 24-Bit Measuring Shield":
Purchase a printed copy of this issue for $10.00. |
Keysight U1282A &
U1242C Cat III/IV
Waterproof True RMS
Digital Multimeters
The new U1282A DMM from Keysight provides a number
of enhancements over its predecessors, including IP67 dust/
water ingress protection, longer battery life (800 hours
from four AA cells), 3-metre drop resistance and a 60,000
count display with a basic DC voltage accuracy of 0.025%.
The U1242C is a lower-cost option with similar features,
including IP67 protection.
Review by Nicholas Vinen
W
E’VE BEEN USING the U1252B
and U1253B DMMs in the SILICON CHIP office for a number of years
now and we like them. The U1282A
appears to supersede these, in the
sense that it offers similar features
and precision but has been furnished
with a number of improvements. It
also employs a larger, more legible
LCD readout without the option of the
previous OLED display and having
compared them side-by-side, we think
the LCD is better.
However, the most obvious improvement has to be the IP67 rating (waterproof up to 1m), which is good news
for anybody who has to work outdoors
or in a wet/dusty environment. The
display is now a 60,000 count type
(those we are currently using are 50,000
count) which means less auto-ranging
and that can only be a good thing.
One feature of our existing meters
we don’t love is their rechargeable
batteries. While this does avoid the
need to open them up and buy new
60 Silicon Chip
cells, all too often we find the battery
goes flat in the middle of a session and
we then have to wait for it to recharge.
The meters reviewed here take a much
simpler approach and use four alkaline
AA cells. You do need to unscrew the
rear cover to replace them but the battery life is now so long that you will
rarely have to do that. Good.
The U1282A claims to last up to 800
hours while the U1242C will run for
400 hours between battery swaps. Of
course, if you make extensive use of the
screen back-light or the inbuilt torch
(on the U1242C), use the continuity
buzzer a lot, etc, you will drain the
battery faster. But given that most of the
time a DMM is being used it’s probably
just measuring voltage or current, you
can expect either meter to last a long
time on one set of cells.
Both new units are tested to withstand a 3-metre drop onto an unspecified surface; presumably a hard one,
since you can’t always arrange to have
carpet or grass underfoot if you happen
to drop them! This, combined
with the IP67 rating, suggests
that Keysight are trying to make
these units attractive to electricians
and technicians as well as R&D staff
who would be using them in a lab
environment.
The main differences between the
U1282A and the less expensive U1242C
are the display count (60,000 vs
10,000), basic DC accuracy (0.025%
vs 0.09%), battery life (800 vs 400
hours) and some differences in features
(see below). Otherwise, they are quite
similar in size/appearance and have
the same voltage ratings of 1000V (Cat
III) and 600V (Cat IV).
Extra features
The U1282A and U1242C both have
a “Vsense” feature which means they
contain a non-contact voltage sensor
at the top of the meter which can be
activated with a button press. The
U1282A also has the ability to generate square-wave and PWM signals and
siliconchip.com.au
terface (U1173, pictured). The optical
interface means that not only is the PC
electrically isolated from the meter (and
thus it’s safe to use it “live”) but also it
does not affect the waterproof rating.
In use
has an optional low-pass filter for AC
voltage measurements, to allow for
accurate measurements of chopped
mains voltage signals such as those
used to drive induction motors from
variable speed drives (VSDs).
The U1282A has an AC bandwidth
of 100kHz while its cheaper sister,
U1281A (without Vsense), has a 40kHz
bandwidth. The U1242C has 2kHz AC
bandwidth. Other features the U1282A
has that the U1242C doesn’t include
dual display mode (eg, AC voltage +
frequency) and support for probes with
inbuilt pushbuttons for data hold/logging/saving. The U1282A also has up
to 1µV resolution (compared to 10µV
for the 1242C) and a wider capacitance
measurement range of 1pF to 0.1F
(rather than 100pF to 0.01F).
Interestingly, the U1242C has some
features not present in the more
expensive U1282A models. These
siliconchip.com.au
include “Harmonic ratio” measurement which displays the distortion
level for an AC signal and is intended
for mains waveform analysis. It also
has the ability to make differential
temperature measurements using two
thermocouples and a low-impedance
voltage measurement mode to eliminate phantom readings from stray
fields and capacitive coupling.
Also, as mentioned above, the U1242C
has a rear-mounted white LED torch.
These extra features all seem intended
to be useful for electricians and field
technicians, which makes sense since
the U1242C should do everything they
need and its lower price makes it great
value for such users.
Both units have a data logging mode
which allows them to store a number
of readings to their internal memory,
which can be later downloaded to a
PC using the optional USB/optical in-
So what are they like to use? The
short answer is that they work very
well for day-to-day measurement tasks.
As already noted. the display is easy to
read, with a very quick update rate and
reasonably fast auto-ranging. The LCD
bargraph at the bottom of the screen
is quite handy for viewing rapidly
changing readings. The ambient temperature display with 0.1°C resolution
in the upper-right corner of the screen
is also good.
The volume of the continuity beeper
is impressive and should work well in
noisy environments and if you have
one of the models with Vsense, a red
LED at the top of the unit also lights
to indicate continuity.
Speaking of Vsense, you activate it
by holding down the “Null” button for
1s and the LCD bargraph then shows
the detected magnetic field strength.
Once you bring the top of the unit close
enough to live mains wiring, the beeper
sounds with a particular cadence and
the red LED lights up to let you know.
The range switches have a nice
chunky feel to them and all the modes
are pretty easy to figure out; you would
rarely have to refer to the user manual.
Both units are supplied with probes
with nice sharp tips and they look
like they will stand up to a reasonable
amount of abuse and possibly last as
long as the meters themselves.
Conclusion
The U1242C offers great value as it
is a quality meter with many great features and should suit casual users and
electricians well. The U1282A is better
suited for lab use with its higher precision and less need to switch ranges,
thanks to the 60,000 count display.
If you’re in the market for a quality/value or high-end portable DMM,
either of these two units would be a
good purchase.
To purchase either unit, or make an
enquiry, contact Keysight Technologies by visiting www.keysight.com or
calling 1800 629 485. A list of their
Australia/New Zealand distributors
can be found at www.keysight.com/
main/partnerfinder.jspx?N=1+18763
SC
2+187535&cc=AU&lc=eng
April 2016 61
|