Wat is Ampere en hoe bereken je dat

What is Ampere?

For those less familiar with electric current, we have written a brief explanation. Electric current, expressed in Amperes (A), is the amount of electric charge that flows per second through a conductor, such as a copper wire. It is an important quantity in electrical engineering.

André-Marie Ampère

The Unit: Ampere

The unit Ampere is named after the French physicist André-Marie Ampère (1775-1836), a pioneer in electromagnetism. One Ampere is defined as the current at which one Coulomb of charge flows per second through a conductor. In Ohm's law, you see the relationship: I = U ÷ R, where I is the current in Amperes, U is the voltage in Volts, and R is the resistance in Ohms.

What is electric current?

Electric current is the movement of electric charge carriers (usually electrons) through a conductor. You can compare it to water flowing through a pipe: the amount of water per second is comparable to the current in Amperes.

Common Current Strengths

In practice, you encounter various current strengths:

  • Milliampere (mA): LED lights (20mA), USB chargers (500mA-2A)
  • 1-10 Ampere: Household appliances, lighting, laptops
  • 10-16 Ampere: Washing machines, vacuum cleaners, microwaves
  • 16-32 Ampere: Electric cooktops, water heaters, home charging stations
  • 32+ Ampere: Industrial machines, heavy equipment

Measuring Current

You measure current with an Ammeter or multimeter, always in series with the circuit:

  1. Switch off the power
  2. Break the circuit at the measuring point
  3. Place the ammeter in series (current must flow through it)
  4. Set the multimeter to the correct current setting (AC or DC)
  5. Switch on the power and read the value

Alternating Current (AC) vs. Direct Current (DC)

Direct Current (DC):

  • Current in one constant direction
  • Used in batteries, accumulators, electronics
  • Symbol: ⎓
  • Examples: 12V car battery, USB 5V, solar panels

Alternating Current (AC):

  • Current periodically changes direction (50Hz in Europe)
  • Used in mains voltage, household installations
  • Symbol: ~
  • Examples: 230V mains voltage, industrial 400V

Current and Safety

The current flowing through the human body determines the severity of an electric shock:

  • 1 mA: Barely perceptible, no danger
  • 5 mA: Painful, but not dangerous
  • 10-20 mA: Muscle contractions, difficult to let go
  • 30 mA: Breathing problems, life-threatening
  • 50+ mA: Cardiac arrhythmias, often fatal
  • 100+ mA: Cardiac arrest

That's why residual current devices (30mA) are mandatory according to NEN 1010 – they trip before dangerous currents occur.

Current in Ohm's Law

Current is directly related to voltage and resistance through Ohm's law:

I = U ÷ R

  • I = Current in Amperes
  • U = Voltage in Volts
  • R = Resistance in Ohms

Practical example: A 230V appliance with 23Ω resistance draws I = 230 ÷ 23 = 10A current.

Practical Applications

1. Fuses and circuit breakers

Calculate the maximum current in a circuit to select the correct protection. A 16A circuit breaker protects circuits up to 3680W (at 230V).

2. Power calculations

Power (Watt) = Voltage × Current. A 2300W appliance on 230V draws P ÷ U = 2300 ÷ 230 = 10A.

3. Battery capacity

Batteries are often expressed in Ampere-hours (Ah). A 100Ah battery can theoretically supply 100A for 1 hour, or 10A for 10 hours, or 1A for 100 hours.

4. Residual current devices

Residual current devices detect leakage currents from 10mA (sensitive) or 30mA (standard) and trip within 200 milliseconds for maximum safety.

Types of Current in Practice

Nominal current: The normal operating current of a device or installation.

Inrush current: Short current peaks when switching on (motors, transformers) – can be 5 to 10 times higher than nominal.

Short-circuit current: Extremely high current during a short circuit – must be interrupted quickly by protective devices such as a screw-in fuse or miniature circuit breaker.

Leakage current: Unwanted current via earth or insulation faults – detected by residual current devices.

Conclusion

Understanding current strength is important for safe design, installation, and maintenance of electrical systems. Whether you are installing a simple lighting circuit or managing complex industrial installations – knowledge of Amperes and the relationship with voltage (Volts) and resistance (Ohms) is essential.

 

 

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