Engineer Talks: Kirchhoff’s Laws
Kirchhoff’s laws refer to two principles in electrical circuit theory that deal with the conservation of charge and energy. They are Kirchhoff’s Current Law (KCL) and Kirchhoff’s Voltage Law (KVL).
Kirchhoff’s Current Law (KCL):
Based on the principle of conservation of electrical charge, KCL states that the total current entering a junction in an electrical circuit is equal to the total current leaving the junction.
Imagine a traffic flow at an intersection, where multiple roads converge, and vehicles flow through the intersection.
Suppose three roads lead into the intersection; road A with 10 cars per minute entering, road B with 15 cars per minute entering, and road C with 25 cars per minute leaving.
To satisfy KCL, the total number of cars entering the intersection must equal the number of cars leaving.
Cars entering: 10 cars/minute + 15 cars/minute = 25 cars/minute
Cars leaving: 25 cars/minute
The total current entering an electrical circuit junction equals the total current leaving the junction.
Kirchhoff’s Voltage Law (KVL):
Based on the principle of conservation of energy, KVL states that the sum of electrical potential differences (voltages) around any closed loop or mesh in a circuit is zero. In other words, the energy the power source provides is fully utilized in the series circuit, with no energy lost.
Imagine a series circuit in a string of Christmas lights connected to a power source.
The power source provides 120 V.
Supposing there are 10 bulbs in series, each with a voltage drop of 12 V and the connecting wires have a negligible voltage drop.
According to KVL, the sum of voltage gains and drops around the loop must be zero.
Voltage gain from the power source: +120V
The voltage drop across each bulb: -12V
Total voltage drop across 10 bulbs: 10 x -12V = -120V
To satisfy KVL, the sum of these voltages must be zero: 120V – 120V = 0V
In the case that KVL and KCL are not satisfied:
– It could mean that the analysis is wrong.
– Component damage
– System malfunction
– Safety hazards
DC-DC converters are circuits that convert a source of DC from one voltage level to another, resting on Kirchhoff’s foundations.
The VNW-30W series by Motien Technology is a robust and efficient family of 30W DC-DC converters designed for demanding applications requiring reliable performance.
Encased in a compact 1″×1″ copper package and encapsulated with flame-retardant resin, these converters offer a wide input voltage range of 24V and 48V, with output options including 3.3V, 5V, 12V, 15V, ±12V, and ±15V DC.
With an efficiency of up to 91% and a tight output voltage accuracy of ±1%, the VNW-30W series ensures stable power delivery.
Key features include 1600 VDC isolation, adjustable output voltage, and comprehensive protection mechanisms such as continuous short circuit protection with automatic restart, overcurrent protection, overvoltage protection, and overtemperature protection.
These converters operate effectively across a wide temperature range of -40 to 100°C and support remote ON/OFF control, making them ideal for various industrial and high-performance applications.
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