Megger MIT525 Specifications
MIT515, MIT525, MIT1025
5-kV and 10-kV dc Insulation Resistance Testers
MIT515, MIT525, MIT1025
5-kV and 10-kV Insulation Resistance Testers
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Industry best guard terminal accuracy
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Compact and lightweight for easy
transport and use
PI, DAR, DD, SV and ramp test
Unique dual case design provides
additional user protection
Lithium-ion battery - extended capacity,
rapid charge
Advanced memory with time/date stamp
CATIV 600 V safety rating on all terminals
DESCRIPTION
The new range of insulation resistance testers consists of
three models: two 5 kV units (MIT515 and MIT525) and a
10 kV unit (MIT1025). Resistance measurement is available
up to 10 TΩ for the 5 kV models and 20 TΩ for the 10 kV
model. The new instruments are smaller and lighter than
previous models yet offer advanced features and rapid
charge capability.
A key productivity feature is the ability to take
measurements when connected to line power/mains with
a dead battery. Intelligent battery charging ensures the
optimum charge rate as a function of battery level, resulting
in minimum charge times.
The rugged, unique dual case design provides the ultimate
protection for a portable instrument and a clip-on lead
pouch ensures that leads remain with the instrument at
all times. The case lid is removable for improved terminal
access. IP rating is IP65 with the case closed preventing
water/dust ingress. High reliability and safety are built in;
all models are safety rated to CATIV 600 V and are double
insulated.
Five preset voltage ranges are provided in insulation
test mode, plus a user settable lock voltage range. Any
selectable test voltage may be locked and restored
via the selector switch, thereby increasing efficiency
of commissioning and repetitive tests. Preconfigured
diagnostic tests include Polarization Index (PI), Dielectric
Absorption Ratio (DAR), dielectric discharge (DD), Step
Voltage (SV) and ramp test.
The ramp function gradually increases voltage up to a
selected level while graphing current vs. voltage (graph
downloadable). Graphs can be compared to example
curves in IEEE 95-2002 to reveal a variety of faults difficult
to detect otherwise. Small defects can be easily detected
without risking the sudden large voltage increments
produced by a Step Voltage test. Monitoring the developing
graph during test enables the operator to terminate prior
to breakdown, thereby reducing the possibility of damage
to already flawed insulation. These units are particularly
informative on polyester, asphalt and epoxy-mica
insulations. They can also test voltage suppression devices.
Simplicity of operation is achieved with two rotary switches
and the large backlit display enables multiple results to be
displayed simultaneously.
Advanced memory storage includes time/date stamping of
results, logging of data and recall of results to screen. A
fully isolated USB device interface (type B) is used for safe
transfer of data to Megger’s PowerDB asset management
software.
Typical end users include:
Electrical contractors
Testing and service companies
Wind farm and solar generation operators
Power generation and distribution companies
Industrial companies
Rail companies
MIT515, MIT525, MIT1025
5-kV and 10-kV dc Insulation Resistance Testers
FEATURES AND BENEFITS
Smaller size and lighter weight allows easier transport
and use without compromising performance.
High measurement range enables installation testing and
long-term trending of higher value apparatus.
Unique dual case design allows for fire-retardant
protection while maintaining ruggedness.
High-quality, flexible silicon test leads meet safety
regulations of IEC 61010-31:2008 while ensuring
measurement accuracy.
Timed IR plus PI, DAR, DD, SV and ramp tests maximize
diagnostic testing capability.
Operate from line power when battery fully discharged
(charges while operating).
Two and one-half hour full battery charge time (one-half
hour charge for one hour testing) significantly increases
productivity.
Up to six hours continuous testing (5 kV) on a single
battery charge.
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Industry best guard terminal performance to insure
highest accuracy of measured values.
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Enhanced driver technology provides plug-and-play
when connected to the internet. No tedious and
potentially interruptive setup procedures.
Dedicated voltmeter function (30 V to 660 V) with
frequency measurement allows the user to check for
induced voltages.
CATIV 600 V safety rating on all terminals allows for
safe use in the widest range of applications.
Large LCD with automatic backlight.
Noise filter rejects up to 3 mA noise for effective
operation in electrically noisy environments.
High altitude operation up to 3000 m while maintaining
CATIV 600 V rating.
Rotary switch operation for easy, intuitive field use.
Field replaceable battery.
Locking test leads provide additional safety.
3 mA short circuit current with unique max power
regulations technology ensures maximum transfer
whatever the load until selected voltage is reached.
5% accuracy all the way up to 1 T-ohm at 5 kV and
2 T-ohm at 10 kV ensures highest accuracy where it
matters most.
Date and time-stamped test results reduce the risk of
error in result interpretation.
APPLICATIONS
The units are designed for testing the insulation of highvoltage electric equipment. Their wide voltage range
also allows applications for low-voltage equipment.
Generators, motors, transformers, cables and switchgear all
require effective maintenance. The test techniques on the
instruments provide valuable diagnostic information.
All three instruments test the insulation resistance of:
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High-voltage power cables and high-voltage buses
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Large motor/generator windings
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Line and substation transformers
The MIT525 and MIT1025 also perform spot tests, stepvoltage tests, dielectric discharge tests, ramp tests, and
dielectric absorption tests for the following applications:
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Acceptance testing at installation to check conformance
to specifications.
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Routine preventive/predictive maintenance testing after
installation.
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QA testing as part of the manufacturing process.
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Diagnostic testing to isolate faulty components for repair.
With its higher voltage testing capability, the MIT1025 is the
perfect everyday work tool for manufacturers, users and
maintainers of rotating machinery. Designed in accordance
with the requirements of IEEE43:2000, the MIT1025 is ideal
for measuring the insulation resistance of armature and
field windings in rotating machines rated 1hp (750 W) or
greater. The standard applies to synchronous, induction
and dc machines as well as synchronous condensers.
What is the IEEE Standard 43-2000?
In March 2000, the IEEE-SA Standards Board approved
a revision of IEEE Std 43-1974 by the Electric Machinery
Committee of the IEEE Power Engineering Society. This
revision is IEEE Std 43-2000, the “IEEE Recommended
Practice for Testing Insulation Resistance of Rotating
Machinery.” Following is a brief summary of its highlights:
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Test voltages up to 10 kV are recommended for
windings rated greater than 12 kV.
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Both the insulation resistance and the polarization index
test are recommended.
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Test results should be compared to historical values to
identify changes.
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In lieu of historical records, minimum acceptable values
(based on the type of equipment) for both tests are
indicated.
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Depending on the machine rating, the readings for one
or both tests should exceed the minimum acceptable
values.
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If the readings are below the minimum acceptable
values, the winding is not recommended for an overvoltage test or for operation.
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