Inrush Current Blog Archive

Inrush Current Blog Archive

The inrush current blog archive contains articles relating to inrush current, it's causes, cures, and prevention.

Inrush Current Limiting

limiting heat lamp inrush current

Limiting Heat Lamp Inrush Current Protects Relay Contacts

Limiting Heat Lamp Inrush Current Incandescent heat lamps create a large inrush current when first powered on. Limiting heat lamp inrush current prevents relay damage and extends lamp life. Heat lamps can be used to warm enclosed areas such as livestock pens and chicken coops. Banks of incandescent heat lamps are mounted overhead. As the number of heat lamps increases, limiting heat lamp inrush current becomes more important. Over current can damage relay contacts in … Continue Reading

Protect your RV AC motor with Inrush Current Limiters

Limit AC Motor Inrush Current

Limit Inrush Current In AC Motor Air Conditioning Application AC motors used in air conditioning equipment draw large inrush current at power-on. A recent customer of ours had a 115-VAC air conditioner installed in their travel trailer for park use. This 5,000-BTU unit required 16 amps for simultaneous compressor and blower motor operation. The trailer was also equipped with a load-shedding power distribution panel to protect its wiring harness from overload. If more … Continue Reading

Equations to Calculate Inrush Current

Calculate Inrush Current in Three Steps

Why do I need to Use Inrush Current Calculators to Select an Inrush Current Limiter? An Inrush Current Limiter (ICL) can protect electrical equipment from overheating at switch-on due to inrush current. And, because inrush current equals the maximum instantaneous surge of incoming current from a power source, it can equate to as much as 2-3 times the steady state current of the attached device. So, Inrush Current Calculators are the … Continue Reading

solor-panel for energy efficiency

Alternative Energy Applications for MS35 Inrush Current Limiters

Application Overview Ametherm’s MS35 series inrush current limiting thermistors play a key role in alternative energy applications by avoiding current spikes in the power generated by wind turbines, solar panels, and other sources as it’s fed into batteries, inverters, and other energy storage components. The MS35 devices are also used to regulate the release of battery energy in electric vehicles and in pre-charge circuits for many different types of battery … Continue Reading


Toroidal Transformer Inrush Current Issues Got You Down? We’ve Got the Answer

What You Need to Know About Toroidal Transformer Inrush Current Toroidal Transformer Inrush Current can cause some serious damage if not appropriately managed. Inrush current can cause circuit breakers to trip and fuses to blow. Additionally, it can cause a complete failure of the transformer itself. And if that weren’t enough to give you a headache, excessive inrush current can also limit the total number of devices which can be … Continue Reading


How to Limit DC Motor Inrush Current

Choosing An Inrush Current Limiter To Preserve Your DC Motor So, what does an Inrush Current Limiter have to do with DC motor inrush? More than you may think. DC motor inrush is the maximum, instantaneous input current drawn by the DC motor when first turned on and it is important to know how to limit the inrush current to prevent possible damage to the motor. A DC motor converts electrical energy … Continue Reading


Design Guidelines for a Power Factor Correction (PFC) Circuit Using a Capacitor and an NTC Thermistor

Objective Ametherm inrush current limiters are used in many applications today that require suppression of surge current when power is first applied to the system. One of the popular applications of Ametherm inrush current limiters is in power factor correction circuits. This article provides a solution for finding the correct power factor correction (PFC) circuit for an inductive load. This solution is suitable for applications such as ballasts, LED drivers, … Continue Reading


Enabling Higher Power Efficiency through Thermistor-based Temperature Compensation

By Balaji Santhanam, Hubble Power Systems Mehdi Samii, Ametherm Inc. Originally Published in Power System Design  Magazine  As electronic systems continue to become more compact, temperature plays an increasingly important role in system reliability and power efficiency.  Many engineers are already familiar with how temperature can affect reliability; if a system becomes too hot, device operation can become unpredictable.  Using a simple temperature sensor like a thermistor, the host processor can monitor … Continue Reading


Transformer Inrush Current: Limiting a 40VA Transformer

Have you ever turned on a transformer and heard a loud humming sound? What about having a blown fuse or tripped circuit breaker? These signs can all indicate transformer inrush current. Transformer inrush current describes a spike in current that occurs when you initially turn on your transformer. This spike can be up to 10 times higher than normal current. Why does inrush current occur?  It can happen because large transformers demand a huge amount … Continue Reading


PTC Thermistors vs. NTC Thermistors for Inrush Current

Today we’re going to cover how you can improve inrush current protection for your equipment, machinery or system using NTC and PTC thermistors. Inrush current affects a wide range of products. It becomes further complicated by systems that switch on and off quickly, such as welding equipment and HVAC systems. This post will give you a brief overview of the topic. For more information, you can read the full article here. What … Continue Reading

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