Datasheet
METRAHIT27M, 27I and H+E CAR
Milliohm Resistance Meter and Digital Multimeter,
Insulation Tester and Data Logger
2 GMC-I Messtechnik GmbH
Applications
The METRA HIT 27 is a compact, rugged and reliable instrument,
which is equally suitable for precision measuring and recording
tasks in the factory, for on-site service and in the laboratory:
• Adjustment of shunts in instrumentation
• Testing of electrical connections at conductor bars for open-
pit mining, in potential bonding systems, and for industrial and
household applications
• Testing of cable resistance, wiring, shunt resistors in PCBs
and thick-film circuits
• Measurement of contact resistance in relays, contactors and
power interrupters
• Testing of resistance in fuses, as well as conductor resistance
in heavy current circuits
• Testing of winding resistance in transformers, coils, small
motors etc.
• Testing of discharge resistance on aircraft, and at aircraft outer
skin components
• Contact resistance testing in uninterruptible power supplies
• Measurement of cell voltages, for example in on-board
batteries and emergency power supplies
• Contact resistance testing at welding seams
The new METRA HIT H+E
CAR (hybrid & E-CAR) is a measuring
instrument for testing the electrical safety of electric and hybrid
vehicles. It includes, among others, the following tests and mea-
surements:
• Protection against direct contact during charging and dis-
charging
• Protection against indirect contact during discharging (battery
in the vehicle) and charging of the traction battery
• Insulation and dielectric strength (insulation resistance
between all electric components of the high voltage system
and the vehicle frame)
• Insulation of the battery (insulation resistance between the high
voltage battery poles and the metallic tray/vehicle frame)
• Voltage of capacitors
• Protection type of electric equipment
• Testing of charging regulators
• Testing of electric motor (nominal voltage, power, speed)
General
The METRA HIT 27 milliohm resistance meters are the modern
alternative for the well known TH2 (Thomson) and Wh2
(Wheatstone) measuring bridges. They provide an expanded
measuring range, greater accuracy and easier reading. As
universal measuring and test instruments, they acquire and
record values to an integrated memory module including
resistance in the milliohm and micro-ohm ranges, as well as
“normal multimeter resistance values” in the ohm to mega-ohm
ranges by feeding a measuring current to the resistor, conductor
or contact under test. The respective measuring current is
determined by the rotary selector switch setting and lies within a
range of 1 to 0.02 A in the milliohm ranges. The instrument also
measures and records insulation resistance (METRA HIT 27I only)
with test voltage selectable in steps, for example in order to test
resistance in on-board electrical systems for aircraft, ocean going
vessels etc., and for testing overvoltage arresters and much
more.
Easy Operation
Operation is very easy. Simply connect the low-resistance device
under test to the instrument with the included measurement
cables, Kelvin clips or 4-pole probes (KC27), and select the ideal
measuring range.
Integrated Measured Value Memory and Interface
Each METRA HIT 27 is equipped with a measured value memory
module and can thus be utilized as a data logger or a recording
instrument for all measuring functions. Measurement results can
be transmitted to a PC either off-line via the optical interface
which is furnished as standard equipment, or online with an
optional bidirectional adapter. In this way, for example,
characteristic voltage and temperature curves (see figure below)
can be displayed and analyzed in line recorder format relative to
real-time, or individual measured values, e.g. voltages for each of
the cells in a storage battery, can be saved with the DATA Hold
function and analyzed at a PC in tabular form.
METRAwin
10/METRA HITMETRAwin
10/METRA HIT (software
option):
Recorded characteristic temperature curve and triggering
characteristics (2-channel recording with 2 METRA HIT
instruments) plus evaluation at a PC
METRAwin
10/METRA HIT Software Option
Measurement data recorded to the measured value memory
module can be evaluated at a PC if required with the help of the
IR interface supplied as standard equipment and a bidirectional IR
adapter (BD adapter) with conversion to the RS 232 protocol.
METRAwin
10/METRA HIT software (see above figure) is
recommended to this end, and is suitable for display, analysis and
documentation of measurement results using Windows
98, NT,
2000, XP, VISTA or 7. The software is available as an accessory.
User-friendly complete packages (e.g. the BD Pack or the
complete METRA HIT 27AS case) are easy to connect and install
and include everything required for high performance
measurement data processing.
Offset Balancing
Automatic offset balancing is provided for the lower measuring
ranges. Manual offset balancing, as required with the METRA HIT
17 predecessor model, is thus no longer necessary.
Protection Against Operator Error
The METRA HIT 27 is safeguarded against erroneous short-term
connection to devices under test with fault voltages of up to
600 V by means of protective devices.
Test Functions and Automatic Functions
All METRA HIT 27 instruments are equipped with diode and
continuity test functions, as well as automatic and manual
measuring range selection and battery shutdown.
Lower limit
136,2°F
Lower limit
136,2°F
Alert ON
Alert ON
Upper limit
140,9°F
Upper limit
140,9°F