INT-1532-L-5-L-010 TE Connectivity, INT-1532-L-5-L-010 Datasheet - Page 51

• Manufacturer Part Number: INT-1532-L-5-L-010
• Description: DIGITAL PANEL METER, 4-DIGIT, 57.7V TO 139V / 100V TO 240V
• Manufacturer: TE Connectivity

Specifications of INT-1532-L-5-L-010

• No. Of Digits / Alpha: 4
• Meter Function: Digital
• Meter Range: 0mA To 20mA
• Digit Height: 96mm
• Supply Voltage Range: 57.7V To 139V / 100V To 240V
• Power Consumption: 3W
• Rohs Compliant: NA

Total Harmonic Distortion
Harmonic problems are almost always introduced by the consumers’
equipment and installation practices. Harmonic distortion is caused by
the high use of non-linear load equipment such as computer power
supplies, electronic ballasts, compact fluorescent lamps and variable
speed drives, which create high current flow with harmonic frequency
components. The limiting rating for most electrical circuit elements is
determined by the amount of heat that can be dissipated to avoid
overheating busbars, circuit breakers, neutral conductors, transformer
windings and generator alternators.
Definition
THD is defined as the rms value of the waveform remaining when the fundamental is
removed. A perfect sine wave is 100%, the fundamental is the system frequency of 50
or 60Hz. Harmonic distortion is caused by the introduction of waveforms at frequencies
in multiplies of the fundamental, ie: 3rd harmonic is 3x the fundamental frequency /
150Hz. Total harmonic distortion is a measurement of the sum value of the
distorted waveform.
Power measurement
Despite the use of good quality test meter instrumentation, high current flow can often
remain undetected or under estimated by as much 40%, despite the use of good
quality test-meter instrumentation. This severe under-estimation causes overly high
running temperatures of equipment and nuisance tripping. This is simply because the
average reading test meters commonly used by maintenance technicians, are not
designed to accurately measure distorted currents, and can only indicate supply
conditions at the time of checking. Power quality conditions change continuously, and
only instruments offering true rms measurement of distorted waveforms and neutral
currents can provide the correct measurements to accurately determine the ratings of
cables, busbars and circuit breakers.
Neutral currents
High harmonic environments can produce unexpected and dangerous neutral currents.
In a balanced system, the fundamental currents will cancel out, but, triple-N’s will add,
so harmonic currents at the 3rd, 9th, 15th etc. will flow in the neutral. Traditional 3-
phase system meters are only able to calculate the vector of line-to-neutral current
measurements, which may not register the true reading. Integra 1530, 1560 and 1580
offer a 3-phase 4-wire version with a neutral 4th CT allowing true neutral current
measurement and protection in high harmonic environments.
Harmonic profiles
There is much discussion over the practical harmonic range of a measurement
instrument, however a study of the harmonic profiles of typically installed equipment
can guide the system designer to the practical solution. A typical harmonic profile graph
will show a logarithmic decay as the harmonic frequency increases. It is necessary to
establish the upper level at which the harmonic content is negligible.
Example:
A laptop switch mode power supply causes approximately 25% of 3rd harmonic, 19%
of 5th harmonic, 10% of 7th harmonic and 5% of 9th harmonic, etc. Therefore, it is
clear that almost all the harmonic content in an IT dominated load will be below the
15th harmonic.
In a 3-phase load incorporating 6-pulse bridge technology as is common in many
variable speed drives, UPS systems and dc converters, similar profiles will be observed
which also extends to the 25th and 27th harmonic. It can therefore be deduced that in
the majority of industrial and commercial applications, an instrument measuring up to
the 31st harmonic is ideal.
Costs
Harmonic currents add to the fundamental load current and can affect revenue billing by
introducing errors into kilowatt hour metering systems, which will directly increase the
net billable kilowatt demand and kilowatt hour consumption charges.
The commercial effects of harmonic distortion to power quality are dramatically shorter
equipment lifetimes, reduced energy efficiency and a susceptibility to nuisance tripping.
The costs of supply interruption are high, however caused, resulting in data corruption,
disruption of process manufacturing and failure of telecommunications facilities etc.
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