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Voltage

 

Electricity is the movement of electrons from one atom to another. The flow of electrons through an electrical conductor is called electrical current. The electrical pressure necessary to cause this movement is voltage. Voltage itself does not flow through conductors, but is the force that causes current (measured in amperes) to flow. Voltage is also called electrical potential, because if voltage is present in a conductor, there is potential for current flow.

Voltage rating is a function of a circuit breaker's ability to suppress the internal arc that occurs when a circuit breaker's contacts open. The voltage rating specified for Carling Technologies' circuit breakers represents the maximum voltage allowable for the breaker to function properly at the rated current. Carling offers both AC (alternating current) and DC (direct current) voltage ratings.

AC/DC

AC or alternating current is an electric current or voltage that reverses its direction of flow at regular intervals and has alternately positive and negative values, the average value of which over a period of time is zero. The number of times this value changes (or cycles) per second is it's frequency. Frequency is measured in Hertz (Hz). The more cycles per second, the higher the frequency. The electrical "grid" in the North America is based on a very stable 60Hz frequency. Most European countries are based on a 50Hz frequency. All of Carling Technologies' AC voltage ratings are listed at 50/60Hz.

DC or Direct Current is an electric current or voltage which may have pulsating characteristics, but which does not reverse direction.

Every Carling Technologies' circuit breaker will have a maximum AC and/or DC voltage rating stamped on its label. This rating is based on the combination of circuit configuration, current coil rating, frequency, number of poles (or phase), and the applicable regulatory agency requirements. In the case of multiphase/multi-pole circuit breakers, this rating will represent the maximum line-to-line voltage.

Electrical Tables Available

Additionally, for each Carling Technologies' circuit breaker product series we offer on-line PDF files that provide electrical tables that detail the relationship between all of these elements. Below is an example of such an electrical table. In this case, the table represents the A-Series Handle circuit breaker as a component supplementary protector.

Using this table the following can be calculated:

  • The maximum rating for a circuit breaker with Series Trip circuit, 25 amp current rating, single-phase 50/0Hz AC voltage would be 277VAC.
  • The maximum rating for a circuit breaker with Series Trip circuit, 25 amp current rating, three-phase 50/0Hz AC voltage would be 250VAC
  • The maximum rating for a circuit breaker with Series Trip circuit, 25 amp current rating, DC voltage would be 80VDC

The PDF files that contain the electrical tables, along with other specifications can be found on the specific series' product page within this web site.

NOTE: The voltage rating of a circuit breaker must be equal to or greater than the circuit voltage. The voltage rating of a circuit breaker can be higher than the circuit voltage, but never lower. For example, a 277 VAC circuit breaker could be used on a 125 VAC circuit. A 125 VAC circuit breaker could not be used on a 277 VAC circuit.

Ratings

Carling Technologies' circuit breaker maximum DC voltage ratings range from 65 VDC (M-Series, D-Series) to 80VDC (A-Series, B-Series, C-Series) to 125VDC (C-Series UL489, E-Series, F-Series). Maximum AC voltage ratings range from 240VAC (C-Series UL489) to 250VAC (M-Series) to 277VAC (A-Series, B-Series) to 480VAC (C-Series, D-Series) to 600VAC (E-Series, F-Series).