Specially designed to cure arcs in electromechanical connectors! These magnetic arc extinguishing properties need to be understood!

Latest update time：2023-12-06

Reads：

Q: Magnetic arc quenching in DC applications

Some electromechanical contactors rated for HVDC (High Voltage Direct Current) loads have permanently built-in "arc quenching magnets" that help "extinguish" or cut off the arc that forms when the connector is disconnected. This increases the DC rating of the connector and helps extend electrical life at rated load. Although arcing may occur when the connector is closed, the arc generated when the connector is open is much larger.

Some limit switches , automotive relays and power relays (above 2A) also have this function.

Magnetic arc quenching properties are listed on the DigiKey website under the "Features" filter. But the precursor is that the product specification specifies that the product has magnetic arc-extinguishing properties. However, even if a product has this feature, the data sheet may not list it. If the product has a polarized output, it most likely has this feature.

Generally speaking, electromechanical contactors with a polarized DC rated output can handle current in both directions, but only when the connector is closed, and the polarity must be correct when the connector is open. If the connector is disconnected with incorrect polarity, it will have the opposite effect, i.e., increase arcing, accelerate damage to the connector surface, and potentially create a hazard. AC load devices generally do not require arc-extinguishing magnets because when the connector is disconnected, the AC waveform crosses the zero point and extinguishes the arc itself.

To determine which product is suitable for your application, review the Connector Life Cycle Rating or On - Off Chart under specified test conditions in the data sheet .

Some specifications also list connector on / off times, including arc duration:

Electromechanical arc extinguishing applications:

Electric vehicles - used to speed up high voltage DC charging and safely switch off and disconnect current loads

Renewable Energy and Power Inverters - Solar and Wind are used to safely switch and disconnect DC loads during the inverter process and when transferring energy storage to and from the battery

Manufacturing and Industry - used in energy storage or backup systems, drones or fleet management, or even in forklift charging systems

Instructions for Sensata :

All Sensata Gigavac contactors can carry bidirectional current on the closed connector. The term "bidirectional" refers to the ability to switch/break when current is flowing. Most Sensata Gigavac contactors are designed and optimized to break current in the direction of current flow for maximum current breaking capability. We also offer contactors in a bidirectional design. Such devices are typically implemented by changing the direction of an internal arc-quenching magnet.

polarization:

The power terminals on polarized contactors are labeled positive (+) and negative (-). This marking is used to guide the correct installation of the product. Most contactors have an internal arc-quenching magnet that disconnects the load (opens when current flows). This is especially important for disconnecting loads 48V and above. Arc extinguishing magnets are designed for the flow of electrical current in a specific direction. Improper installation may limit the effectiveness of the arc-quenching magnet or render it ineffective and significantly shorten the contactor's life. In applications where the system voltage exceeds 48V, care should be taken to install the contactor in the correct direction of current flow. A properly installed contactor should allow current to flow into the positive (+) terminal and out of the negative (-) terminal.

Bidirectional:

If a two-way contactor is used, the mains terminals can be connected in any direction. Internal arc-quenching magnets are configured to break the arc that forms regardless of the direction of current flow.