DLRO200 Digital
Micro-Ohmmeter - Features

Description
The Megger DLRO200 measures resistance between 0.1µΩ and 1Ω, at high currents. The versatile instrument can provide test currents from 10 amps up to 200 amps subject to the load resistance and supply voltage. A large liquid crystal display provides all the information needed to perform a test; all test parameters and measurement results are displayed.

The high current capability and compact design make the DLRO200 suitable for testing circuit breaker contacts, switch contacts, busbar joints or connections or other applications where high current is needed. The on-board memory will store up to 300 sets of results; as well as adding notes to the stored results, the alphanumeric keyboard allows you to set the test current and value required. The instrument will check the continuity of the test circuit, and will quickly ramp the test current up to the desired level.

The keyboard is also used to set upper and lower limits for the result and to prevent the use of excessive currents by setting an upper limit to the allowable test current. It uses a four-terminal measurement technique to cancel the resistance of the test leads from the measurement.

• Small and weighs less than 15kg.
• Test currents from 10 amp to 200 amp DC.
• 0.1µΩ best resolution.
• On-board memory for up to 300 test results plus notes.
• RS-232 port to download stored results or for real time output to a printer.
• Supplied complete with 5 meter test leads and download software.

The DLRO200 operates in one of three modes, which are simply selected from the on screen menu.

Continuous Mode
Continuous mode is provided for users who wish to monitor a resistance over a period of time. Connect the test leads, select the test current and press the TEST button. The DLRO200 will pass a current continuously, and measure the resulting voltage at two-second intervals, until the test button is pressed to stop the test or the test circuit is interrupted.

Normal Mode
In normal mode you connect the leads, select the test current and press the TEST button. The test current will ramp up to the desired level, hold for two seconds and then ramp down. The whole process takes approximately ten seconds.

Auto Mode
In auto mode select the desired current, connect the current leads and press the TEST button. The TEST lamp will flash to show that the DLRO200 is ready to carry out a test. As soon as the potential leads are connected, a test will start. To repeat a test, simply break contact with the voltage probes and remake contact.

Application
Measuring individual joints in a busbar is a good example of the convenience to be gained by using AUTO mode. The two current leads are connected to the ends of the busbar. They will remain connected here until all tests have been completed. When the voltage leads make contact across a joint, the DLRO200 detects that all four leads are connected, carries out a test and stops. When you move to the next joint DLRO detects the new completed circuit automatically and carries out the next test, and so on until all joints have been tested. The results may be stored automatically and may be recalled to the display or downloaded for review.