A multimeter will measure the current and resistance between two leads. You can use it to identify faulty components and broken connections. But the device cannot help you unless you learn how to interpret its findings.
What Is Infinite Resistance On Multimeter?
- If the current stops flowing, it will conclude that the conductor in question has a high resistance. Multimeters typically register infinite resistance in response to open circuits. An open circuit doesn’t allow the current to flow because of a faulty part or a broken connection.
- The multimeter can also detect a high resistance because you flipped the switch of the electronic component to the off position. If the circuit is closed, the multimeter will detect minimum resistance because the current can flow unimpeded.
To understand the definition of infinite resistance, you have to keep the following in mind:
1). What is Resistance
Let’s understand this concept by comparing electricity to water flowing through a pipe. Water can only flow through a pipe if it doesn’t have obstacles.
If you clog the pipe, the water may continue to flow, but the flow rate and volume will drop. Electricity is the same.
Think of the resistance as the obstacle in a water pipe. When a current flows through a conductor, it will encounter opposition.
Technically speaking, if you have zero resistance, the current is infinite.
If the pipe is free of obstacles, the water can flow freely at full capacity without any opposition.
But the opposite is also true. If the pipe is completely blocked, the water cannot flow.
In the case of a conductor, if you have infinite resistance, the current has stopped flowing. Something has obstructed the flow of electricity, which is why the multimeter has registered infinite resistance.
Just because the multimeter has registered infinite resistance doesn’t mean the resistance is actually that high. A multimeter determines the resistance by measuring the flow of current.
The people at Right Channel Radios have pictures of multimeters that illustrate this concept.
From the images, you can see that touching the probes together closes the circuit. The needle responds by showing zero resistance. But if you separate the probes, the multimeter registers infinite resistance because the circuit is open.
The best conductors offer the least resistance. Though, circuits have resistors that regulate the electrical flow by introducing resistance. In other words, resistance isn’t necessarily a bad thing.
2). How Do You Measure Resistance?
You quantify resistance using Ohms. ‘Ohms’ is a unit of measure named after the German scientist that discovered the concept of electrical resistance.
A multimeter determines the resistance by computing the flow of current.
You place the multimeter’s probes on each end of the component you want to test. The readings will tell you everything you need to know.
A higher resistance produces a lower current and vice versa.
Can There Be Infinite Resistance?
Infinite resistance is not real. It exists theoretically. If you have zero resistance, the current will flow unimpeded. But if you have infinite resistance, the current will stop flowing.
This is why multimeters respond to open circuits by displaying an ‘Infinite Resistance’ reading. They interpret the absence of flowing current as a sign that a component has very high resistance.
Additionally, if you have significant resistance and a tiny power source, the resistance is more or less infinite in comparison to the small power source. However, practically, some of the current from that small power source can still flow despite the resistance.
Insulation is a better example. Insulation is supposed to resist the flow of electricity. However, it has finite resistance. Electricity can still flow through insulation. Therefore, infinite resistance doesn’t exist.
You may see it in theoretical calculations, but you won’t find it in real life.
If you tested your component and it showed infinite resistance, check the switch. Did you leave it in the ‘ON’ position?
Look for any compromised parts and connections. A reading of infinite resistance shows that you have an open circuit. This isn’t true in every case, but it should be your first consideration.
What Does Infinite Resistance Look Like On A Digital Multimeter?
If you have an ohmmeter, the device points to the infinity symbol if the circuit is open. With an analog multimeter, the needle swings to the far left of the display.
Digital multimeters are much easier to read because they display an ‘O.L’ symbol.
What Happens When Resistance Is Infinite?
Infinite resistance leads to zero current. Resistance opposes the flow of current. The higher the resistance, the lower the flow of current. If the resistance is infinite, the current will stop flowing altogether.
But as you now know, the resistance measured by a multimeter is not necessarily infinite despite what the readings might say. The multimeter cannot measure the resistance directly.
Instead, the device determines the resistance by quantifying the flow of current. If the current stops flowing, the multimeter will display a reading of infinite resistance. You have to keep that in mind before you start assuming that your conductor has infinite resistance.
Does OL Mean Infinite Resistance?
‘OL’ is a sign of infinite resistance on the display of a fluke meter.
Do I Need To Fix Multimeter Infinite Resistance?
You need to fix infinite resistance. A reading of infinite resistance shows that you have an open circuit. The equipment you want to test doesn’t have infinite resistance.
Rather, it has a fault that won’t let the current pass. Sometimes, this shows that your equipment or appliances are dead. In other cases, it signifies a malfunction, one you can fix. But you have to troubleshoot the equipment to identify the factors responsible for the short or open circuit.
Make sure the multimeter works.
If the multimeter is fine, make sure you connect the probes to the correct points on the equipment you want to test. If you’ve handled the multimeter appropriately, but you continue to record infinite resistance, check the appliance.
Is it switched ON?
You don’t have to plug the equipment into a power source to test it. In fact, it is a bad idea to use a multimeter on an appliance that has electricity running through it. You will get the wrong readings.
Unplug the appliance but make sure you’ve flipped the switch to the ‘ON’ position. Otherwise, you will record infinite resistance because of the open circuit.
A reading of Infinite resistance is only problematic if you don’t know what it means. Once you understand that it simply shows that current cannot pass, you can use the reading to troubleshoot your equipment.