What is Open Circuit Voltage or OCV?


Open Circuit Voltage (OCV)

Welding processes require voltage in the range of 15 to 40 volts,, and current in the range of 50 Amp to 400 Amp, normally for SMAW, TIG, MIG MAG and FCAW. In welding, Open Circuit Voltage or OCV (simply no-load voltage) is the voltage (In volts) between the electrode and the work piece(or the earth) when welding is not in progress. So, OCV is the voltage exists between negative and positive pole of a welding machine in ON mode but without starting the weld.

As you can see in below example, OCV is the voltage when circuit is open that mean no welding. The closed circuit voltage takes place during welding & explained further in this article.

Why OCV values kept maximum 80 Volts?

As we know, the maximum safe limit of voltage is 80 volts for a human body. A higher voltage above this limit can be lethal for the living organisms. Simply, higher the open circuit voltage or OCV, easier to strike arc because of the initial higher voltage pressure, but more risk to electric shock. Being 80 Volts a safe limit of electric hazard for human, welding power source are designed to have maximum OCV of 80 Volts.

what is the value of open circuit voltage of a welding transformer/ Welding machine?

Typically values of OCV for welding machines are within the range of 50V – 80V for SMAW, MIG-MAG, FCAW & SAW Welding. A OCV within the range of 50 to 80 volts helps in easy striking of the arc, thus benefits the welders in easy weld start.

what is close circuit or operating voltage?

  • Closed circuit voltage is the voltage measured across the arc during welding that means the voltage found among the work-piece and the electrode holder during welding. It will vary depending upon type of electrode, polarity, arc length & current type. Typically, the closed circuit voltage is runs between 15 – 40 volts.

How is OCV different from Welding Voltage?

Open Circuit Voltage should not be confused with Welding Voltage. Welding voltage is the voltage that exists between the electrode and the job (or the earth) during welding, and this is what maintains the arc between the electrode and the job.

Welding voltage will typically be much lower than OCV, and will vary with many parameters (such as arc length, etc.)

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