Considerations For Choosing A DC Contactor

voltage dc contactor

Considerations For Choosing A DC Contactor

Component selection is essential for the safety and dependability of systems since the mechanical opening of a DC circuit under load invariably results in arcing, which needs to be managed and put out. You may choose the best high voltage dc contactor suppliers in China by using the following factors.

The Clarification of The Real Application

Understanding the rated insulation voltage and rated operating current required for your application is crucial. Specifying the voltage is usually easy, but defining the current is where the initial issues come from. The mean current flowing during regular operation is the rated operating current, or it is also common as the thermal continuous current.

The rated operating current heats the contactor, which is dependent on the contact resistance of the primary contacts (controlled by the contact material and the contact force). The makers of DC contactors specify the rated operating current under precise environmental conditions.

Therefore, the actual permitted value may differ under real-world operating circumstances. Overshoots of around 25% are common, for instance, if the DC contactor is mounted in a vented control cabinet. When specifying, things must be in clear discussion separately with the manufacturer.


The circuit’s Inductance

Apart from the current and voltage readings, the circuit’s inductance is another important element that can have a big impact on the breaking capacity. The inductive characteristics cause a voltage peak, which depends on the inductance’s size and raises the arc’s intensity. For example, the breaking capacity of the Schaltbau C294 DC contactor improves by 300% if the circuit’s time constant can be lowered from 15 ms to 1 ms (by lowering the inductance).

Bidirectional Applications

Contactors for unidirectional applications are precise to disconnecting currents in a single direction. Bi-directional contactors are perfect for all energy-recovery applications since they can consistently manage both current directions. Energy storage systems, where batteries charged and then discharge again, are a common example of this. These contractors can also be important in DC charging stations, battery-powered cars, and regenerative systems.

Examining the Short Circuit

As with any application, one must keep an eye out for short circuits. In the case of a short circuit, avoid damage to the DC contactor if it properly matches to the main fuse. It must also be final if the contactor’s switch status has to be under watch over to add safety features. If so, a feedback circuit is important for the contactor.

Service Life of Mechanical and Electrical Components

The application determines the required service life of a DC contactor. Here, the distinction is actually between the electrical (switching cycles under a defined load) and mechanical (no-load switching cycles) service lives.

In several modern applications, such as battery storage and the automobile industry, the contactor often flips off when there is no load. The contactor initiates the galvanic separation, but not before the power electronics control the power. The need in this instance is related to the mechanical service life, which is significantly greater by energy storage connector suppliers in China.

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