Shunt A shunt has different meanings in various fields. The most common
is a precision low-resistance component in the electronics and power industry, used for high-current measurement and range extension. I. Electronics / Power Industry (Most Common) 1. Core Definition and Principle - Nature: A low-resistance, high-precision power resistor (in
milliohm/microohm scale).
- Principle: Connected in series in the measured circuit. A high current
produces a millivolt-level voltage drop (U=I×R), and the current is
calculated indirectly by measuring the voltage.
- Typical specifications: Rated voltage drop is mostly 75mV/100mV. For example, 100A/75mV
corresponds to a resistance of 0.75mΩ.
2. Main Applications - High-current measurement: Used with millivoltmeters / multimeters to measure high DC
current (from dozens to tens of thousands of amperes).
- Range extension: Connected in parallel with a low-range ammeter to shunt most of
the current, allowing only a small portion to pass through the
meter.
- Current sampling: Used for current monitoring and protection in BMS, motor control,
power supplies, charging piles, and energy storage systems.
3. Key Parameters and Selection - Rated current: Ranges from 5A to 15kA.
- Rated voltage drop: 60mV, 75mV, 100mV, 150mV, etc.
- Accuracy: 0.1%, 0.2%, 0.5%, 1%, etc.
- Material: Usually manganin alloy (low temperature coefficient, good
stability).
- Heat dissipation: High-current applications require good heat dissipation to
prevent accuracy loss due to temperature rise.
4. Advantages and Disadvantages - Advantages: Simple structure, low cost, high DC accuracy, suitable for high
currents.
- Disadvantages: Voltage drop loss, heat generation, non-isolated, and accuracy
affected by reactance at high frequencies.
II. “Shunt” in Other Fields 1. Network Shunt (Traffic Replication / Load Balancing) Copies / forwards network traffic for monitoring, auditing,
intrusion detection, and load balancing. 2. Hydraulic / Pneumatic Shunt Distributes fluid evenly to multiple outputs, used in hydraulic
systems and lubrication systems. 3. Faucet Shunt (Household) One-inlet, multi-outlet water splitter with independent switches,
used for washing machines, showers, etc. III. Usage Notes - Must be connected in series in the measured circuit.
- Rated current should be higher than the actual maximum current (20%
margin recommended).
- Secure wiring to reduce contact resistance; four-wire connection is
recommended for high-precision measurement.
- Pay attention to heat dissipation to avoid overheating.
- Mainly used for DC or low-frequency AC; use with caution in
high-frequency applications.
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