When designing the electric circuit of the car, whether it is the introduction of a powerful audio system, the installation of a preheater or the organization of charging an electric car, the owner inevitably faces the question of the throughput of wiring and protective devices. Often in the specifications of equipment or on the labeling of fuses, a value of 63 amperes is found, and it is here that it becomes necessary to translate the current strength into an understandable amount of power - kilowatts. Understanding this dependence is critical to preventing wiring overheating and fire.
The direct answer, β63 amperes equal to such and such a number of kilowatts,β does not exist without knowledge of the voltage in the network. In the automotive industry, we often operate with tension. 12 volts. for passenger cars or 24 volts. for freight transport, while in domestic conditions or when charging electric cars from the network, we are talking about 220 volts.. An error in determining the voltage during the calculations can lead to fatal consequences for electrical equipment.
In this article, we will discuss in detail the physical meaning of these values, give specific calculations for different types of voltage and explain why the circuit breaker at 63A can be either redundant or insufficient depending on your tasks. You will learn to quickly assess the load and select the appropriate components.
The physical essence of current and power
To correctly interpret the value of 63 amperes, it is necessary to return to the basics of electrical engineering. Current strength (Ampera, A) is the amount of electric charge passing through the cross-section of a conductor per unit time. An analogy can be drawn with a water pipe: amperes are the volume of water flowing through the pipe per second. However, the volume of water alone does not indicate what work it can do.
Power (Watts, kW) is just the value that shows what useful work is done by electric current. In our analogy with water, power would also depend on the pressure in the system (voltage). The formula linking these quantities in a DC circuit is simple: P = I Γ Uwhere P is power, I is current, U is voltage. It is the knowledge of voltage that allows you to translate abstract amps into specific kilowatts.
Importantly, in AC circuits, which we encounter when charging electric vehicles from a home outlet or industrial grid, another parameter is added to the equation. power factor (cos Ο). For active loads (heaters, incandescent lamps), it is equal to one, but for motors and pulsed power supplies it can be less, which reduces the real usable power at the same 63 amperes.
β οΈ Note: Never use the AC (220V) calculations when designing the vehicleβs on-board network (12V). These are different physical processes, and confusing them means that you are guaranteed to disable expensive equipment or short circuit.
Power calculation in the onboard network 12 volts
Consider the most common scenario for passenger cars, where the voltage of the onboard network is 12 volts. If we are talking about a fuse or a 63-amp automatic, the maximum power that such protection can pass through itself is calculated by the formula: 63 A Γ 12 V = 756 W. However, in reality, the voltage in a working car is rarely exactly 12 volts.
When the engine is started and the generator is working properly, the voltage in the network rises to the 13.5-14.5 volts. In this case, the power corresponding to the current of 63 amperes increases to 850-910 W. This is an important nuance for those who install high-power Hi-Fi or Hi-End audio systems, where amplifiers can consume significant current at peak moments.
Why would you need such a current in a car? 63 amperes is a serious load. For example, a standard electric motor of a cabin stove consumes about 10-15 amps, dipped-beam headlights - about 10 amps (two pieces), and a gas pump - about 5-8 amps. Current 63A is characteristic of:
- π Powerful winches used on SUVs for self-retracting.
- π Professional automotive sound amplifiers with high energy consumption class.
- βοΈ Electrical systems of preheating of the engine or cabin.
When calculating the cross-section of the wire for such a current, the length of the section must be taken into account. For 63 amperes at 12V voltage, the voltage drop over a long area can be critical, so a copper wire is used by at least a cross section. 16 mm2 (and often 25 mm2) to avoid heat and power loss.
Power 63 Amps in 24 Volts (Trucks)
In the commercial vehicle segment, which uses trucks, buses and special vehicles, the de facto standard is 24 volts. This is done to reduce current strength at the same power transfer, which allows for the use of smaller-sized wires and reduces losses in long vehicle wiring. Here the calculation formula changes, doubling the final power result.
At 63 amperes and 24 volts, we get: 63 A Γ 24 V = 1512 W or 1.51 kW. If you take into account the increased voltage of the operating generator (about 27-28 volts), the power can reach 1.76 kW. This is already comparable to the power of household appliances such as a microwave or a powerful hair dryer.
In trucks, a current of 63 amperes is often found in power chains:
- π Air conditioning systems and autonomous heaters (Webasto, Planar).
- β‘ Starter circuits (although the starterβs starting current is much higher, operating currents can be in this range).
- π Sockets for connecting household appliances in the driver's cab.
Particular attention should be paid to contact groups. At 24V and 63A, spark formation during circuit breakup may be more intense than in a 12-volt network. Therefore, relays and switches must have an appropriate safety margin and DC marking (for direct current).
When replacing the standard safety lock with 63A in the truck, make sure that the new safety lock has a characteristic type (e.g. slow-blow) identical to the original to avoid false positives at initiation currents.
Transfer of 63A to kW for charging electric vehicles (220V)
With the development of electromobility, the question of β63 amperes how many kWβ most often arises in the context of charging stations. Here we move into the world of alternating current (AC) with a voltage of 220 volts (single-phase network) or 380 volts (three-phase). The 63A circuit breaker is the standard for high-power home charging stations or industrial outlets.
In a single-phase network 220V, the calculation looks like this: 63 A Γ 220 V = 13,860 W or 13.86 kW. This is very high power for a home network; a standard home outlet typically withstands 16A (3.5 kW). To connect such a load, a separate inlet cable and a dedicated line from the shield are required.
If you are talking about a three-phase network 380V (which is often found in garage cooperatives or charging stations), the formula is complicated and includes the root of three (1.73): P = β3 Γ U Γ I. The result is 1.73 Γ 380 V Γ 63 A β 41,450 W or 41.45 kW. This is a level of fast charging, capable of replenishing the power reserve of an electric car in a matter of hours.
Below is a summary table showing how power changes at the same 63 amperes current depending on the type of network:
| Type of network | Voltage (B) | Current (A) | Power (kW) | Application |
|---|---|---|---|---|
| passenger-network | 12 | 63 | 0.76 | Audio, winches. |
| Bortseed cargo network | 24 | 63 | 1.51 | Heating, machinery |
| Home Network (1 phase) | 220 | 63 | 13.86 | EV charging, house entry |
| Industrial (3 phases) | 380 | 63 | 41.45 | Fast charging. |
β οΈ Attention: A 63-amp machine for a 220V network requires a cable with a minimum of 16 mm2 (copper) cross-section. Using a thinner wire, such as a standard 2.5 mm2, will cause the insulation to instantly ignite before the machine even goes off.
Selection of cable cross-section and line protection
Knowing that 63 amps is a significant power requires a lot of conductor selection. The main enemy of electric current is resistance, which converts some of the energy into heat. The thinner the wire, the higher the resistance and the more it warms when passing current in 63A.
For automotive wiring (12V) at current 63A, the minimum permissible cross-section is considered to be 16 mm2However, for long stretches (more than 2-3 meters) it is highly recommended to use a wire. 25 mm2 or 35 mm2. This reduces the voltage drop at the amplifier or winch terminals, ensuring their maximum efficiency.
In the 220V network, the requirements are dictated by the Power Installation Device Rules (PUE). For the machine 63A, the copper cable must have a cross section of at least 10β16 mm2 depending on the method of laying (open or in the pipe). Aluminum cables require more cross-section, but their use in new wiring is limited.
The most important element is not only the cable itself, but also the quality of connections. The plugs, bolts and tips shall be designed to have a current of at least 63A. Using cheap twists or weak clamps will lead to local overheating and melting of contacts.
βοΈ Checking line readiness at 63A
Characteristics of automatic switches
When choosing 63 amperes protection, you can not take the first machine you find. They are divided into classes according to the time-current characteristic, denoted by the Latin letters B, C, D. Automotive applications (winches, pumps, audio systems) and chargers most often require class machines. C or D.
Class B machines are fast and are designed for active load networks (lighting, heaters). If you put such a machine on the electric motor of the winch, it will knock out at each start due to the initiation current, which can briefly exceed 63A several times. Class C can withstand short-term overloads of up to 5-10 denominations, which is ideal for engines.
It is also worth paying attention to the disconnecting ability. For a car, this is not as critical, but for a home charging station (220V), it is better to choose devices with a shutdown capacity of at least 6 kA (6000 Amps). This ensures that the machine does not explode when short circuit in the network.
Why is the machine body melting?
If the body of the 63A machine begins to melt, it is almost always a sign of poor contact at the place of connection of the wire, and not overloading current. A weakened clamp screw increases resistance, causing heat.
Typical errors in the calculation of loads
The most common mistake is ignoring the starting currents. The consumer looks at the rated power of the device, sees that it is less than the calculated power of the 63A, and puts protection. However, at the time of inclusion, the current can grow by 5-7 times, which will lead to instantaneous