Combat Electrical Arcing in Circuits with Suppressor/Snubber Network Devices for Relays

Posted by Sean Ek on Aug 21, 2024 8:15:00 AM

Electrical arcing can cause any number of issues in a circuit that lead to unreliable operation. Without effective snubbing, arcing is associated with early failures in relays, switch contacts and solid-state components (e.g., SCRs and TRIACs). 

Network Devices for Relays

Knowles’ Cornell Dubilier brand offers a series of RC-type arc suppressor/snubber components, the QAS series, that combats arcing by providing single-device RC networks in two-lead radial packages. These networks can extend the operating life of electronic devices by dramatically reducing or eliminating arcing at the point of electrical contact. QAS series devices are also effective at reducing spark-generated EMI/RFI that can cause noise and interference.  

Each device in the QAS series consists of metallized polyester capacitor RC network, coated with a flame-retardant epoxy. Designing with one single device containing an RC network, rather than building with discrete networks, results in a more compact and robust output. 

Key Series Specifications: 

  • 24 devices
  • Capacitance values of up to 1.0uF 
  • Resistor values up to 680 ohms 
  • Rated voltage options up to 1600 Vdc/660 Vac, 60 Hz 
  • Operating temperature ranges from –55 °C to +85 °C at full rated voltage

How Arc Suppressor/Snubber Network Devices Work 

For direct current (DC) voltage applications, the RC network is usually connected across the relay contacts and for alternating current (AC) voltage applications, the RC network is connected across the load.  

When the contacts in an arc suppression circuit open, voltage is applied across the capacitor instead of the relay contacts. No arcing occurs because the capacitor charges in a shorter amount of time than it takes for the contacts to open.  

When the contacts close, current from the charged capacitor and the source can exceed the safe conductance of the contacts. At this point, the resistor in the network is responsible for limiting that inrush of current, reducing arcing, and ultimately, extending the service life of the contacts.  

To learn more about Knowles’ Cornell Dubilier brand QAS device specifications, visit https://www.cde.com/new-product/QAS/

Topics: Military and Aerospace

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