Cropico DO6, Руководство пользователя

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DO6 Handbook
Jan 2006 4 of 107 pages
1. Introduction
1.1 Use
Fast and accurate measurements of ultra-small resistances can be made using the DO6
milliohmmeter. With its rugged table-top case and membrane keypad, this instrument is
designed for both laboratory use and harsh industrial environments.
Temperature-compensated resistance-testing of wires and coils is possible using a Pt100
sensor or pyrometer to measure he temperature of the device under test. He instrument then
corrects the resistance to e.g. 20
°
C (selectable)
The meter has a huge range of applications, such as measuring:
•
Transformer / motor windings
•
Coils of any kind
•
Cables and wires on the drum or as meter samples
•
Switch and relay contacts
•
Heating elements
•
Connections and contacts to power rails, and
•
much more
Complete control capability via the RS232 PC interface means that fully automatic test
stations can be set up. The meter includes a PLC interface for integration in production
process controllers. A 2-way comparator with PLC and relay switching outputs is also
provided for classification and selection of the devices under test.
1.2 Description
The meter works on the basis of the proven 4-wire measurement method, in which test-lead
resistances and contact resistances are eliminated. The measurement technique also
compensates automatically for any thermal EMF’s in the measurement circuit. The
instrument leads are monitored for damage by a built-in detector.
Of course the meter includes temperature compensation for any type of material under test
such as copper, aluminium, brass, tungsten etc. using an externalPt100 sensor or external
infrared thermometer (accessory) to measure the temperature. A special circuit for protecting
the measurement input when measuring high-inductive devices has been developed to prevent
damage to the meter from voltage peaks produced when disconnecting the device under test.
If there is a requirement to test devices using different parameters in an automatic test setup,
then up to 16 device settings such as measuring range, limits, temperature coefficient etc. can
be saved. All device-specific settings are shown on the display.
The settings can be retrieved via the keyboard or PLC interface using a bit pattern (4 bits). Of
course all device settings can also be made via the RS232 interface.
A backlit, high contrast LCD display is used for displaying the readings, so it is extremely
easy to read the measurement in both dark and well lit rooms.