What is DLRO Testing?
Electrical issues can occur almost anywhere where there are electrical circuits. They can be anything from problems with electrical circuits in someone’s house to electrical issues found in a chemical plant. For issues that could interrupt entire electrical systems, it is important to know how to diagnose those issues. This is where the DLRO test comes in. This blog will go over what DLRO testing is and what is needed to perform that test.
What is DLRO Testing?
DLRO testing, or Digital Low Resistance Ohmmeter testing, is a type of continuity testing that measures low electrical resistances (<1 ohm) for electrical components and connections. These tests seek out weak connections, contaminants, and corrosion by sending a current through a closed circuit. Closed circuits should allow the electricity to loop throughout the circuit at a consistent rate. If there is an issue in the way the electricity flows through
the circuit, it is up to the DLRO to discover what the issue is.
There are three types of measurements done for DLRO testing: two-wire, three-wire, and four-wire. While the two and three-wire methods are utilized for general assessments, the four-wire method is the most common measurement type, and thus, will be the primary focus in the section below.
Four Wire Kelvin Method
The four-wire Kelvin method is a critical technique used in DLRO testing to ensure highly accurate low-resistance measurements. Unlike two-wire measurements used by standard multimeters, the four-wire method employs two separate pairs of leads: one pair to inject the test current and another to measure the voltage drop across the component. This separation eliminates errors caused by the resistance of the test leads and contact points, which is essential for detecting micro-ohm resistances. By isolating the voltage measurement from the current path, the four-wire Kelvin method provides precise readings, making it vital for testing components like busbars, circuit breaker contacts, or cable joints in high-current systems.
Can You Use Other Tools to Perform DLRO Testing?
For those of you with a background in working with electricity, the duties of a DLRO may seem very familiar. As alluded to earlier, digital multimeters, or DMMs, also look into the resistance of electrical circuits; however, they are not quite as
precise as DLROs. For those of you without a background working in electricity, let’s discuss this in further detail.
The primary difference between these two devices is the measurement range each device provides. While both tools operate at a few volts, DLROs provide a much broader range of current as opposed to multimeters. DLROs can provide current anywhere between 10 – 600A, where multimeters can only operate somewhere between 5 – 200mA. Not only this, but DLROs' resistance readings are much more accurate than multimeters. For reference, multimeters can measure down to a hundredth of an ohm, while DLROs can give readings down to the micro-ohm (which is roughly 10,000x more accurate).
For DLRO testing specifically, DLROs are better because as soon as the DMM user requires readings below a hundredth of an ohm, the DMM will just read zero. This can be dangerous because the user will always be at risk reading the DMM’s zero as no resistance, when the circuit could have .0001 ohms. This precision is necessary to ensure there are no false readings when performing DLRO testing.
Why DLRO Testing is Important?
DLRO testing is crucial for discovering abnormal electrical resistances. When the current is too low or too high, the circuits are at risk of becoming damaged, which could interrupt its full electrical system. DLROs are designed to measure wide
amp ranges within very small ohm ranges. What this means is that DLROs can provide a circuit with a lot of current, and measure the resistance provided by the circuit thousands of times more accurately than a multimeter.
To put it another way, think about multimeters as tools your electricians would use to find electrical issues in your house or in low-level industrial situations. To compare, DLROs are commonly used in chemical plants, aircraft manufacturing, and refineries. In industries with significant resistance problems, unwanted heating and energy losses can occur from high resistance, which could potentially lead to increased energy costs or danger.
How ATEC Can Help
ATEC rents out a plethora of DLRO test equipment from leading manufacturers such as Megger, AEMC, Phenix, and Vanguard that can aid you in your next DLRO test. Some notable pieces of test equipment include:
.png?lang=en-US&height=133&width=200 "AEMC-6292-(1).png")
Reach out to ATEC today to learn more about what tools you can use to complete your next DLRO test.