A fuse is an electrical device like a breaker that breaks the circuit if there are current surges or a short circuit exists in the circuit. If there is an overloading condition, the metallic filament of the fuse burns. So it must test the fuse to make sure that it has an accurate structure and condition that can protect your circuit or connected device in case of any fault. Here we will discuss how to test the fuse with a multimeter and check if it is accurate for any circuit. Let’s get started.
Introduction to Fuse
A fuse is an electronic device made for the protection of cables, power supply lines, and instruments if there is a high temperature and power surges exist from opening the circuit to a high current. The fuse has a metallic element that can flow a restricted current. If there is overloading or a short circuit, a high-current-heated fuse element causes the gap in the fuse. As a result of that gap, the current flows into the fuse and completes the circuit. That saves the circuit from any damage, and then the faulty fuse is replaced with a new one after clearing the fault.
How Fuse Works
The fuse comes with a metallic wire that has a certain value for the melting point. Commonly used materials for wire are aluminum, lead, copper, etc. If the current that passes through the circuit is higher than the defined value, the fuse wire will melt as a result of the high temperature caused by the high temperature. As a result, the circuit will break and stop the current flow.
The fuse working principle is based on power dissipation. that is
P = I²R
If the current increase in the fuse increases the power dissipation according to the formula, the resulting wire in the fuse gets heated. When temperatures increase, that increases resistance, and as a result, power dissipation increases. It increases until the melting point of the wire is obtained and the fuse is melted.
How to check if a fuse is blown
It is a simple method to check that the fuse is bad. We can easily check if the fuse is bad by putting in a light and checking that the wire is broken or connected. If there is a burn mark or broken wire, change the fuse. But there is a chance that in circuits, it is not easy to find the wire connection that may be behind any materials. In this case, there is a need to test the fuse to determine its accuracy.
Types of Fuses
Plug-Type Fuse
This fuse is part of circuits that have low current and low voltage. The operating conditions of these fuses range from 0.5A to 30A and up to 150V. It is commonly used in protection devices.
Knife Blade Fuse
It is known as an NF fuse and is part of power distribution circuits. It protects large-sized electrical devices such as motors and drivers. Its operating range is 2A to 1600A. Its two ends are configured on the base and come with knife blades.
Automotive Fuse
These fuses are used in vehicles for the protection of electrical components. They are used for circuits that have a rating of about 32 V DC. But some fuses have a rating of 42 volts that can be used in electrical systems. With their use in vehicles, they are also part of electrical devices.
Cartridge Fuse
This type of fuse is used in circuits for protection from overloading. It has a cylindrical structure and connection point. It is made of porcelain.
How do I test a fuse with a multimeter?
To check whether the fuse or cartridge is working well or damaged, make the connection between the red probe with a VΩmA socket and the black probe with a COM socket on the multimeter. For testing, touch one probe of meter on one point of the fuse and another probe with another end. Any probe can be connected to any side of the fuse.
Continuity test
- To enter the continuity check mode, twist the meter knob and choose a symbol to produce a sound wave on the panel.
- If there is a beep sound, it means the circuit is working in the fuse, no broken connection exists, and the fuse is in good condition.
- If there is no beep on the meter and a large resistance value is shown, it means the wire is broken.
Resistance test
- Set the meter knob to the resistance value over the front panel. Set the value of resistance that has to be measured. Note down the resistance value on the meter. A small resistance means the fuse is working well, and a high resistance means the wire is broken.
Voltage test
- Move the meter knob to select voltage measurement. Select AC voltage if the fuse is connected to the AC circuit and DC for dc circuits. On the circuit.
- Check the voltage value on the meter screen.
- If the voltage on the screen is close to the provided voltage, the fuse is broken.
- If there is no voltage across the fuse, it means the resistance of the fuse connectors is zero and the fuse is working well.
 Fuse Types | Material | Current Rating |  Application |
Breaking Capacity
|
Glass Tube | Glass, metal | 0.5A to 30A | Electronics, | Low to medium |
Blade | Plastic, metal | 1A to 40A | Automotive | Medium |
Ceramic | Ceramic, metal | 0.5A to 100A | Industries | High |
HOW DO I TEST THE FUSE OF A CAR WITH A MULTIMETER?
- Remove the power connected to the fuse box.
- Remove the fuse from the fuse box. Then check the exposed wire in the fuse. If no wire exists, a fuse is good. If there is exposed wire, it means the fuse is damaged.
- Make the connection of one probe of the meter with the exposed wire in the fuse. The second probe has a metallic tab on the fuse box side.
- On the meter, set it to ohms mode.
- If the fuse is bad, the reading is infinite, and if the fuse is good, the value is zero.
Results Interpretation based on test
Test Type | Reading | Details |
Continuity | Beep / Low Resistance | The fuse is good, |
Continuity | No Beep / Infinite Resistance | Blow fuse |
Voltage | Voltage Present | Circuit is working, fuse is good |
Voltage | No Voltage |
 blown fuse
|
Resistance | Very Low Resistance | Working fuse |
Resistance | High or Infinite Resistance | Fuse is blown |
Fuses: Common Problems
- The fuse can be blown, which is a common issue with fuses. A blown fuse is the result of overloading circuits.
- A loose connection is also a problem with use. It occurs when the fuse is not accurately connected to the socket.
- The fuse gets corroded, which can have a bad effect on circuit operation due to the brittle nature of the fuse.
- If the fuse is damaged, it can cause problems for the circuit.
- The fuse has a certain rating, so it is used according to the circuit. If the circuit has the wrong rating, the fuse causes issues in the system.
Faqs
Write down the down the functions of the fuse.
- It saves devices from damage due to faulty circuit conditions.
- It stops overloading damage in circuits.
- It saves short circuits.
- It saves circuits from damage due to circuit mismatching.
What should resistance be in a fuse?
- Set meter leads on one end of the fuse. Another probe is on the second side of the fuse. If the reading is from zero to five ohms, the fuse is working well. A high reading means the fuse is damaged.
What are two ways to test a fuse?
- A multimeter measures AC and DC voltage, resistance, and current flow. To test a fuse, we can use it for measuring continuity in homes; that is a resistance test.
How do you detect a fuse failure?
- Delta voltage and delta current algorithms help detect fuse failure. If there is enough negative variation in voltage amplitude without enough change in current amplitude detected for each phase distinctly,.
Can a fuse be bad for continuity?
- When the fuse is damaged, there is no continuity. If there is continuity, the fuse is good. The best option is to check resistance and then check continuity.
Can you test a fuse in a circuit?
- To check if the fuse is broken or working well, measure the voltage between the fuse on one side and the ground and another side to the ground. Voltage must be equal; if there is no voltage similar, a broken connection exists. For this, the voltage between fuse endpoints can also be measured.
Should a fuse have resistance?
- As compared to devices that are connected to a circuit, a fuse must have less resistance. It helps fuse wire melt easily if there is high current flow in a circuit.
Can a multimeter test all types of fuses?
- The multimeter has features to test different types of fuses, such as glass tube fuses, blade fuses, ceramic fuses, etc.
Is it safe to test a high-current fuse with a multimeter?
- It is safe to test a high-current fuse through a multimeter. But there is a need to make sure the ampere rating of the meter is higher than the fuse to save the meter from any damage.
How many volts should a fuse have?
- Most low-voltage power distribution fuses come with a 250-voltage rating. The voltage rating of fuses should be equal to or higher than the circuit voltage. There can be highs but not lows. Such a 600-volt circuit can be used for a 208-volt circuit.
Markings on the fuse carry which type of information?
- It has data such as the ampere rating, voltage rating, and interruption rating.
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