Firstohm‘s Superior Anti-Surge Wire Wound Axial Resistor SSWA Series With a low-temperature coefficient and a wide temperature range

In the wake of the global outbreak of COVID-19 since 2020, many business leaders have completely rethought their operational philosophy. Not long ago, those enterprises were just considering how to implement smart manufacturing concept, which is now accelerated to accomplish as a result of the prevalence of the epidemic. IoT infrastructure, combined with an AI management platform and robot arm for smart production, has been accelerated in various industries, resulting in intelligent manufacturing. FIRSTOHM also began moving towards smart manufacturing last year, aiming to increase production capacity and customer value.

New Releases of Firstohm's Homepage

01 Sep 2021——FIRSTOM completed the development of its new official website during the second quarter. It launches the Superior Anti-Surge Wire Wound Axial Resistor SSWA Series.

New On The Block: Superior Anti-Surge Wire Wound Axial Resistor (SSWA Series)

Application

• The soft-start resistors for Industrial Invert

• Charging and discharging resistors for Electric Vehicle

• Pre-charging resistor for Power Bank system

• ECG cables

Features

• Superior Wire Wound Resistor which is the best alternative to KOA and VISHAY.

• Unique composite wire wound structures (wire wound + thin film) provide enhanced surge resistance.

• With a low-temperature coefficient and a wide temperature range, it is suitable for working in high-temperature environments.

• Approval of multi-national patents pending.

Structure

The Soft-Start Application Of Inverter

Inverter soft-start resistors are also known as current limit resistors or pre-charge resistors. The main benefit of using a soft-start circuit is to reduce the stress on the electronic components when power is ON, improve the reliability of the system, and extend the life of other components.

The soft-start circuit is connected to high-value resistances in series, and these resistors are also connected to a relay in parallel. When the Inverter is power ON, the relay is disconnected state, and the resistor restricts the current flow, which indirectly slows the rate of voltage change. When the soft-start is complete, the relays are connected and create a low resistance path, so the current will pass mainly through the relays and the system will return to normal operation, allowing for a higher power.

According to the above description of the inverter's action, when the inverter is being started, the voltage rises rapidly, causing an inrush current. It is therefore very important to select the right soft-start resistor. Along with long-term inrush current withstand, the FIRSTOHM SSWA series is cost-effective and offers a smaller size with more advantages than traditional aluminum resistors or cement resistors.

Case Study: The Soft-Start Of 1.5KW Inverter

FIRSTOHM suggested alternatives as below

a.) Evaluated circuit:

b.) Test conditions:
Charging RES. : SSWA05S,120R,5%
Input voltage: 746.7V
Capacitor: 220μF
Ambient temperature: 85℃
Charge/Discharge: ac: 59 SEC. & bc: 1 SEC.
Number of switching: 100,000

c.) Test result: Passed!
Pre-test: 123.44Ω
Post-test: 124.17Ω
△R: +0.591%