**What is Loop Voltage Rise or Voltage Drop?**
In an electrical circuit, voltage can either rise or drop as you move around the loop. Starting from the positive terminal of a power supply and returning to the negative terminal, you pass through various components. The reference point is typically the negative side of the power supply. When moving through a load or a component that opposes the current flow, this is considered a **voltage drop**. On the other hand, when passing through a voltage source that supports the current flow in the same direction, it's called a **voltage rise**.
**What is the Difference Between Voltage Rise and Voltage Drop?**
To distinguish between them, imagine choosing a direction around the loop and assigning polarity to a component’s voltage (positive and negative). If your path goes from the positive to the negative terminal of a component, that’s a **voltage drop**. If you go from negative to positive, that’s a **voltage rise**. This concept is crucial for analyzing circuits using Kirchhoff’s Voltage Law (KVL).
**Understanding Circuit Loops**
A circuit loop must be closed for current to flow. In DC circuits, the current starts at the positive terminal, flows through the components, and returns to the negative terminal. For AC circuits, the current alternates direction, but the loop still needs to be complete—whether it’s a three-phase system or a single-phase system with a neutral or ground return.
**Voltage Drop Measurement**
Voltage drop occurs when part of the power supplied is lost due to resistance in the circuit. To measure it, you take the voltage at the source and compare it to the voltage at the end of the line. The difference between these two values is the **voltage drop**.
For example, if a substation supplies 220V and your home receives 215V, the voltage drop along the transmission line is 5V. This helps identify issues like long wiring, poor connections, or incorrect wire sizes.
**Checking for Normal Voltage Drop**
Voltage drop testing is a common method used to detect excessive resistance in a circuit. A normal circuit should have minimal voltage drop, while a faulty one may show higher than expected values. Common causes of increased resistance include:
- Thin wires that can’t carry enough current.
- Corroded switch contacts.
- Loose or tangled connections.
When repairing, always use properly sized cables to reduce resistance and ensure safe operation.
**Measuring Voltage Drop – The Accumulation Method**
This method involves placing a digital multimeter across a component or wire to measure the voltage drop. The red probe should be connected near the power source, and the black probe should be placed close to the ground. Once the circuit is turned on, the meter will display the voltage drop across the section being tested.
If a large voltage drop is detected—such as 4.1V between a battery and a light bulb—it indicates a problem in that part of the circuit.
**Measuring Voltage Drop – The Step Method**
The step method is particularly useful for low-voltage systems, such as those found in computer control systems. These systems are sensitive to even small changes in resistance. By measuring the voltage drop at different points in the circuit, you can identify bad connections, improper installations, or corroded components.
For instance, if a connection in the circuit causes a 4V drop, it’s a clear sign that the connection needs to be repaired.
**Voltage Drop Calculation Methods**
There are several ways to calculate voltage drop depending on the type of circuit. One common formula is:
**Method 1:**
$$
\Delta U\% = I \times R
$$
Where:
- $ I = \frac{P}{1.732 \times U \times \cos\theta} $
- $ R = \frac{\rho \times L}{S} $
- $ P $ = Power
- $ U $ = Voltage
- $ \cos\theta $ = Power factor
- $ \rho $ = Resistivity of the conductor (e.g., 0.018 Ω·mm²/m for copper)
- $ L $ = Length of the wire
- $ S $ = Cross-sectional area of the wire
**Allowable Voltage Drops:**
- Single-phase: $ V_d = 220V \times 5\% = 11V $
- Three-phase: $ V_d = 380V \times 5\% = 19V $
**Method 2:**
$$
\Delta U\% = K \times I \times L \times V_0
$$
Where:
- $ K $ = 3 for three-phase four-wire, 1 for single-phase
- $ I $ = Operating current
- $ L $ = Length of the line
- $ V_0 $ = Voltage per ampere per meter (from standard tables)
These calculations help engineers design efficient and safe electrical systems by ensuring that voltage drops remain within acceptable limits.
Butt Connector,Lugs Insulated Female Connectors,Insulated Female Connectors,Non-Insulated Spade Terminals Wire Connector
Taixing Longyi Terminals Co.,Ltd. , https://www.txlyterminals.com