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HomeBlogWhat Is a Snubber and Why Do You Need One in Your Electrical Systems?
on July 9th

What Is a Snubber and Why Do You Need One in Your Electrical Systems?

This article delves into the important role of snubbers in electrical systems, explaining how they work, the impact of voltage transients, the different designs and materials used for snubbers, and their applications in various industries. Understanding how snubbers work and how to use them, engineers and technicians can better protect their systems from the harmful effects of transients, ensuring their electrical setups last longer and work reliably.


1. Importance of Snubbers in Electrical Systems
2. Understanding Voltage Transients
3. Different Snubber Designs and Their Materials
4. Types of Snubbers
5. Snubbers Applications Across Industries
6. How to Use a Snubber?
7. Conclusion

Simple Snubber Circuit

Figure 1: Simple Snubber Circuit

Importance of Snubbers in Electrical Systems

Snubbers are special circuits made of resistors, capacitors, and sometimes diodes. Their main job is to control sudden changes in voltage and current, known as transients. These transients can happen when you turn electrical devices on or off, or due to external disturbances like lightning or load changes. Without snubbers, these sudden changes can damage components, cause electromagnetic interference, or lead to system failures.

Taming Voltage Spikes

Voltage spikes are sudden surges that can exceed what components can handle, possibly causing insulation breakdowns or arcing. Snubbers, particularly those with resistors and capacitors (RC snubbers), absorb and dissipate this extra energy, reducing the spikes' impact.

Voltage Spikes

Figure 2: Voltage Spikes

Reducing Oscillations

Switching events can create oscillations due to interactions between inductive and capacitive elements. Snubbers help calm these oscillations, making the system more stable and the waveforms smoother.

Improving Switching Performance

Devices like thyristors, transistors, and relays perform better with snubbers. These circuits shorten switching times and reduce wear and tear, which helps the devices last longer.

Boosting Electromagnetic Compatibility (EMC)

By managing transient voltages and oscillations, snubbers cut down on electromagnetic emissions. This is important for meeting EMC standards, ensuring devices work properly in noisy electrical environments.

Some snubbers include diodes to guard against overcurrent situations. These components protect sensitive electronic parts from unexpected high current flows, keeping the system safe and sound.

RC Snubber With and Without

Figure 3: RC Snubber With and Without

Understanding Voltage Transients

Voltage transients, or sudden voltage spikes, are brief but intense changes in electrical circuits. They happen quickly, lasting from microseconds to milliseconds, and can surge to thousands of volts, far beyond the normal voltage range.

Voltage Spikes and Transients

Figure 4: Voltage Spikes and Transients

Causes of Voltage Transients

Switching Events: Heavy machinery operation, electrical circuit switching, or sudden load changes can trigger these. Rapid switching changes the current flow abruptly, causing transient voltages due to the circuit's inductive and capacitive elements.

Lightning Strikes: Direct or nearby lightning strikes introduce high-energy transients into power systems through electromagnetic induction or direct conduction.

Electrostatic Discharge: The sudden release of static electricity generates transient voltage spikes, especially in sensitive electronic environments.

Power Line Faults: Events like line snaps or insulation failures cause abrupt voltage changes, leading to transients.

Effects of Voltage Transients

Damaging Effects on Equipment
Insulation Breakdown: High transient voltages can exceed the insulation's breakdown voltage, causing permanent damage.
Component Failure: Semiconductor devices like transistors and diodes are particularly vulnerable. Transient voltages can exceed their ratings, causing immediate failure or long-term degradation.
Data Corruption: In digital systems, transient voltages can cause glitches and errors, leading to data loss or system malfunctions.
Need for Protective Measures
Surge Protectors: These devices block or short to ground any unwanted voltages above a safe threshold.
Isolation Transformers: Provide galvanic isolation from the main power supply, limiting the passage of transients.
Proper Grounding and Bonding: Effective grounding systems safely dissipate transient voltages to the earth.

Consequences of Ignoring Transient Voltage Spikes

System Downtime: Frequent equipment failures lead to unplanned outages and costly downtime, disrupting business operations and services.

Increased Maintenance Costs: Regularly replacing damaged components and increased maintenance activities can escalate operational costs.

Safety Hazards: There's a higher risk of fire and electric shock incidents, posing serious safety threats to personnel and property.

Different Snubber Designs and Their Materials

 Hydraulic Snubbers

Figure 5: Hydraulic Snubbers

Hydraulic Snubbers

Hydraulic snubbers use fluid to control movement. Inside, a piston moves within a cylinder filled with hydraulic fluid. During normal conditions, the piston glides smoothly, allowing small movements. When a shock hits, valves slow down the fluid, soaking up the energy.

Materials Used:

• Strong steel or stainless steel for high-pressure strength

• Durable nitrile or polyurethane, flexible in different temperatures

• Silicone-based oils, stable across different temperatures

 Mechanical Snubber

Figure 6: Mechanical Snubber

Mechanical Snubbers

Mechanical snubbers use gears or springs to resist quick movements. You can adjust their resistance, making them great where hydraulic fluids aren’t suitable.

Materials Used:

• Tough hardened steel or alloys for durability

• High-grade chrome-vanadium steel, known for its strength and resilience

Viscoelastic Snubbers

Viscoelastic snubbers combine viscous and elastic properties to absorb vibrations. They are perfect for damping vibrations over a wide range of frequencies.

Materials Used:

• Viscoelastic polymers like polyurethane or silicone rubber, which absorb and release energy by deforming and returning to shape

Friction Snubbers

Friction snubbers dampen movement through friction between surfaces. The damping level depends on a spring or mechanism maintaining surface contact.

Materials Used:

• Made from composites or metal alloys for the right balance of friction and durability

• High-strength steel for consistent force over long periods

Pneumatic Snubbers

Pneumatic snubbers are like hydraulic ones but use air or gas instead of liquid. They're used where a clean operation is required, or where hydraulic fluid leaks would be a problem.

Materials Used:

• Made from aluminum or lightweight composites to reduce weight

• Specialized elastomers designed to last and handle gas expansion and contraction

Types of Snubbers

Diode Snubbers

Diode snubbers are like the unsung heroes of the electronics world, especially when it comes to gadgets with motors, transformers, and relay coils. These little guys really shine in direct current (DC) circuits, where it’s super important to keep things running smoothly without pesky voltage spikes or annoying electrical noise. They’re like the bodyguards for your sensitive electronics, making sure nothing gets fried and everything lasts longer. This is need in power electronics with switching devices like thyristors, transistors, and triacs.

DC motor drives prevent motors from giving off a nasty kick when turned off, power supplies stop annoying overshoots and ringing in switching transistors to keep everything steady, and inverter circuits manage hiccups during switching events in renewable energy setups like solar panels and wind turbines.

 Diode Snubber

Figure 7: Diode Snubber

How Diode Snubbers Work

Imagine you have an inductor, a component in your circuit, which tends to resist sudden changes in current. When the current flowing through an inductor is suddenly interrupted, the inductor generates a high voltage spike.

When you flip a switch (which could be a transistor, relay, or any other switching device) that controls the current through the inductor, the inductor tries to maintain the current flow. This is due to the property of inductors, which resist changes in current.

This sudden interruption in current flow causes a high voltage spike across the inductor. This spike can be high enough to damage other components in the circuit. To protect the circuit from this high voltage spike, a diode is placed across the inductor. Under normal conditions, this diode is in reverse bias and doesn't conduct current.

However, when the high voltage spike occurs, the diode becomes forward-biased. This means the voltage across the diode is enough to allow current to flow through it. The diode provides a path for the current generated by the inductor to flow. This helps dissipate the energy stored in the inductor gradually.

As a result, the high voltage spike is mitigated, protecting the circuit components from potential damage. The energy stored in the inductor is safely released through the diode, allowing the system to stabilize.

Pros and Cons of Diode Snubbers

Spike Protection: They clamp down on voltage spikes, keeping your semiconductors safe.
Noise Control: They cut down on electromagnetic interference (EMI) and noise from sudden stops.
Easy and Cheap: Simple design, easy to make, and budget-friendly.
Slow in Fast Situations: They’re a bit sluggish in high-speed circuits, which can slow things down.
Heat Buildup: They get hot when working, so you need to manage the heat.
Fixed Voltage Clamping: They only clamp to a set voltage, which might not work for all situations.

RC Snubbers

An RC snubber is made up of a resistor (R) and a capacitor (C). It's used to manage sudden electrical changes in circuits. When a switch like a relay, transistor, or thyristor opens or closes, the snubber smooths out the resulting voltage and current spikes. The capacitor absorbs these sudden changes, and the resistor dissipates the absorbed energy as heat. This process helps protect sensitive components and ensures the circuit runs more smoothly.

 RC Snubber

Figure 8: RC Snubber

Where RC Snubbers Are Used?

RC snubbers are found in both AC and DC circuits, from industrial machinery to everyday electronics.

Circuit Type
AC Circuits
Reducing Noise
Cuts down on electromagnetic interference (EMI) and radio frequency interference (RFI) caused by devices like motors and transformers.
Improving Power Quality
Minimizes voltage spikes, delivering better power quality to sensitive electronics.
Switch Protection
Prevents false triggering from voltage spikes when used with devices like thyristors and triacs.
DC Circuits
Protecting Power Converters
Shields semiconductor devices in power converters from damaging voltage spikes.
Stabilizing PWM Circuits
Reduces voltage overshoot and ringing in Pulse Width Modulation (PWM) controllers and DC motor drives, improving reliability and performance.

Pros and Cons of RC Snubbers

Simple Design: Easy to add to different circuits.
Cost-Effective: Cheap to make, which is great for mass production.
Versatile: Can be used in both AC and DC circuits, and in a range of voltage levels.
Limited Speed: They might not handle very fast or high voltage spikes well, making them less suitable for high-speed applications.
Heat Dissipation: The resistor releases energy as heat, which can be an issue in small devices.
Need for Tuning: To work effectively, the resistor and capacitor values must be carefully selected for each specific application, which can make them less flexible than more adaptive solutions.

Solid-State Snubbers

Solid-state snubbers are important in electronic circuits because they protect delicate parts from sudden voltage spikes and surges. They manage extra energy by either absorbing it or redirecting it during events like switching a device on or off, or during unexpected occurrences like lightning strikes or power surges.

You'll usually find these snubbers placed across a switch (like a transistor or relay) or near sensitive components. When a harmful voltage spike happens, the snubber kicks in, either sending the excess voltage to the ground or turning it into heat. This keeps the voltage at a safe level, protecting the components further down the line.

Solid-State Snubber

Figure 9: Solid-State Snubber

Types of Solid-State Snubbers

• Varistors

Varistors, or "voltage variable resistors," change resistance with applied voltage. Made from metal-oxide materials, they guard circuits against high voltage spikes. When the voltage gets too high, the varistor’s resistance drops a lot, letting it absorb and dissipate the extra energy as heat, which protects the circuit.

• Zener Diodes

Zener diodes let current flow in the reverse direction when the voltage goes above a certain level, called the Zener voltage. Unlike regular diodes, which block reverse current, Zener diodes conduct in reverse at a specific voltage. This makes them great for voltage regulation and over-voltage protection, when precise voltage clamping required.

Comparing Performance and Suitability

Zener Diodes
Ideal for places with frequent large voltage spikes.
Offer precise voltage clamping.
Handle bigger power surges and absorb more energy than Zener diodes.
Perfect for protecting sensitive electronics.
Respond slower than Zener diodes.
Respond faster than varistors.
Wear out over time as they absorb energy.
Do not degrade much over time.
Suitability in Different Systems
Best for high-energy environments like power grids or factories.
Best for systems needing quick and reliable suppression of transient voltages.
Examples: industrial power supplies, car electrical systems, consumer electronics.
Examples: communication equipment, precision instruments.
Effective in reducing risks from large, unpredictable voltage spikes.
Work well in low-energy environments with small voltage spikes.

Snubbers Applications Across Industries

• Nuclear Power Plants

RC (Resistor-Capacitor) snubbers are good in nuclear power plants for shielding electrical gear from powerful surges during circuit interruptions, in circuit breakers. For example, at the Palo Verde Nuclear Generating Station in Arizona, snubbers protect electrical systems during earthquakes and other operational disruptions. They absorb the energy from these events, keeping electrical components working and safe.

• High-Voltage Transmission Lines

RC snubbers are also useful in high-voltage transmission systems to guard against damage from lightning and switching surges. An example is the Pacific Intertie, a high-voltage direct current (HVDC) transmission system in the U.S. Here, snubbers defend converters and transformers from sudden voltage spikes, boosting the reliability and efficiency of long-distance power transmission.

• Bridge Construction

Mechanical snubbers help control movements in bridge construction caused by heat, wind, and earthquakes. The Akashi Kaikyo Bridge in Japan, the world’s longest suspension bridge, uses hydraulic snubbers to handle the huge forces from wind and seismic activity. These devices help keep the bridge stable and durable.

• Industrial Machinery

In heavy industries, mechanical snubbers are good for turbines and large industrial fans. At the Hoover Dam, turbines are fitted with snubbers to cut down on vibrations and shocks. This is used for extending the machinery's lifespan, reducing maintenance costs, and avoiding operational hiccups.

• Aerospace

In aerospace, snubbers soak up shocks and vibrations during moments like launch and re-entry. The Space Shuttle, for example, used snubbers to shield its internal parts and payload from damage during extreme conditions. These devices is a must for keeping the shuttle’s structure and operations intact under intense stress.

How to Use a Snubber?

Step 1: Determine If You Need a Snubber

First, figure out if your circuit requires a snubber. Snubbers are helpful in circuits with inductive loads like motors, solenoids, or transformers, as well as switching devices such as thyristors, triacs, or transistors that produce voltage spikes when turned off.

Step 2: Choose the Right Snubber Type

Select the appropriate snubber for your circuit. An RC Snubber (Resistor-Capacitor) is great for reducing oscillations and stopping voltage spikes. For protecting diodes in rectifiers and managing both voltage and current spikes, an RCD Snubber (Resistor-Capacitor-Diode) is ideal.

Step 3: Select Appropriate Component Values

Choose the correct values for the components. The resistor (R) dissipates energy and controls the RC circuit's timing, so select it based on power dissipation needs. The capacitor (C) absorbs energy from the voltage spike, so choose it based on the maximum voltage spike and load characteristics. For the diode (D in RCD Snubbers), ensure it can handle peak reverse voltages and forward current without damage.

Step 4: Integrate the Snubber into the Circuit

Place the snubber close to the voltage spike source, across switch or relay terminals. Ensure secure connections and use proper wiring to avoid additional resistance or inductance that could affect performance.

Step 5: Test the Circuit

After installation, test the circuit under normal conditions. Check for reduced sparking at switch contacts, lower noise levels in signal and power lines, and stabilized voltage and current waveforms on an oscilloscope.

Step 6: Maintenance

Regularly inspect snubber components for wear or damage, such as bulging capacitors or discolored resistors. If the snubber isn’t working correctly, verify that component values are accurately calculated and installed, replace worn-out parts, and ensure the snubber is correctly positioned in the circuit.

Using a snubber can protect sensitive components, reduce electromagnetic interference (EMI), and improve the stability and efficiency of your electrical systems. Always check manufacturer datasheets and consider your circuit's specifics when designing and using a snubber.


Incorporating snubbers into electrical system helps improving reliability and longevity. Snubbers control voltage spikes, reduce oscillations, enhance switching performance, and improve electromagnetic compatibility, offer protection against voltage transients. These transients can damage equipment, cause costly downtimes, and pose safety risks. Various snubbers, like diode, RC, varistors, and Zener diodes, each have specific benefits. Their applications in industries such as nuclear power, high-voltage transmission, industrial machinery, and aerospace underscore their importance. Proper selection, integration, and maintenance of snubbers are good for engineers to protect components and ensure smooth system operation. As technology advances, snubber remains in designing efficient and safe electrical systems.

Frequently Asked Questions [FAQ]

1. What is a Snubber Circuit?

A snubber circuit is an electrical component that controls the voltage and current transients in electronic circuits. It does this by absorbing sudden spikes in voltage and smoothing out current fluctuations, thus protecting sensitive components like semiconductors and switches. A snubber circuit consists of a resistor and a capacitor connected either in series or parallel, depending on the specific needs of the circuit they are protecting.

2. Why is a Snubber Needed?

Snubbers are needed in circuits that handle high voltages or rapidly switching currents, such as those found in power converters, motor drives, and relay circuits. Without snubbers, these transients can cause arcing, electromagnetic interference, and even damage to components due to overheating or excessive stress. Snubbers safeguard the longevity and stability of electrical systems.

3. What is a Snubber Tool?

A snubber tool isn't a widely recognized term in electrical engineering. If referring to physical tools, it's likely a misunderstanding. However, "snubber" generally points to the snubber circuit itself or software tools used for designing snubber circuits, which calculate the optimal values of resistors and capacitors to mitigate electrical transients effectively.

4. What is the Function of a Snubber in a Compressor?

In the context of compressors, particularly those in refrigeration and HVAC systems, a snubber can be used to protect the pressure sensors from sudden pressure surges and spikes. These pressure changes can occur during the compressor's start-up or shut-down phases. Damping these pressures, the snubber helps in maintaining accurate sensor readings and prolonging the life of the sensor.

5. What is the Capacity of a Snubber?

The capacity of a snubber circuit refers to its ability to handle specific voltages and currents. This capacity is determined by the specifications of the resistor and capacitor used in the circuit. The resistor’s power rating and the capacitor’s voltage rating matters. Capacitors might be selected based on their ability to withstand transient voltages, while resistors are chosen for their ability to dissipate energy without overheating. The exact capacity varies based on the application's electrical characteristics and the nature of the transients that need to be managed.

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