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Introduction of shunt

Author: Tanssion Date: 2023-08-15 Hits: 0

Ⅰ. Dimensions, packaging and manufacturing materials of shunts
Ⅱ. Working principle of shunt
Ⅲ. How to choose a shunt
Ⅳ. The main function of the shunt
Ⅴ. Types and functions of shunts
Ⅵ. Design and construction of the shunt
VII. The Role of Shunts in Electronic Test and Measurement
Ⅷ. Application of shunt

A splitter is an electronic device used to split an input signal into two or more output signals. It is often used in electronic circuits to distribute signals to multiple devices or circuit branches for signal sharing and distribution.

A shunt is a device designed to provide a low resistance path for current in a circuit. It is commonly used to divert current away from a system or component to prevent overcurrent. Shunts are commonly used in a variety of applications including power distribution systems, electrical measurement systems, automotive and marine applications.

Shunts are generally used to expand the current range with a fixed value of low resistance. Usually connected in parallel with the moving coil of an ammeter or galvanometer. There are two kinds connected inside and outside the meter.

Ⅰ. Dimensions, packaging and manufacturing materials of shunts

1. Size:Shunts can range in size from tiny packages to relatively large devices, depending on the frequency range, power requirements, and mechanical constraints of the application. In radio frequency (RF) and high frequency applications, size is often affected by wavelength, with higher frequencies likely requiring smaller sizes.

2. Encapsulation:The shunt can be packaged in various forms to suit different application environments and connection requirements.

Common packages are:

Connector package: The shunt may have a connector for easy connection with other equipment.

SMT Package (Surface Mount Technology): Used for high-density circuit boards and tiny size applications.

Box Encapsulation: For larger size shunts, providing better shielding and protection.

Microstrip package: In radio frequency circuits, microstrip packages are often used to maintain high frequency characteristics.

3. Manufacturing materials

Ceramic: Used in high frequency applications, providing excellent insulation and thermal resistance.

Semiconductor materials: used in integrated shunts in radio frequency and microwave applications such as integrated circuits and microstrip lines.

Metal: Metal materials are used for packaging and shielding to reduce electromagnetic interference.

Ⅱ. Working principle of shunt

A shunt is a low ohmic resistor that can be used to measure current. Always use a shunt when measuring currents that exceed the range of the measuring device. Then connect the shunt in parallel to the measuring device.

Shunt resistors have low resistance. It provides a low resistance current path and is connected in parallel with the current measuring device. Shunt resistors use Ohm's law to measure current. The resistance of the shunt resistor is known. and connected in parallel with the ammeter. So, the voltage is the same.

The shunt is actually a resistor with a small resistance value. When a DC current passes through, a voltage drop is generated for display by the DC ammeter; the DC ammeter is actually a voltmeter with a full-scale value of 75mV.

The DC ammeter and the shunt are used together; for example, the shunt resistance of the 100A ammeter is 0.00075 ohms,

That is, 100A*0.00075 ohms=75mV;

The shunt resistance of the 50A ammeter is 0.0015 ohms;


Ⅲ. How to choose a shunt

1. Select the rated voltage drop specification of the shunt according to the mV number marked on the dial of the ammeter (or current and voltage dual-purpose meter) used (usually 75mV or 45mV). If the ammeter used does not have this value, use the following formula to calculate the voltage limit of the meter, and then select the rated voltage drop specification of the shunt.

Voltage limit (mV) = current (A) at the full scale of the ammeter × internal resistance of the ammeter (Ω) x 1000

2. Connect the two current terminals of the selected shunt to the power supply and the load respectively, and connect the potential terminal to the ammeter. It should be noted that the polarity of the terminals of the ammeter must be connected correctly, and the range of the ammeter will be expanded to the current value calibrated on the shunt. .

3. Select the rated current specification of the shunt according to the current range to be expanded.

4. Determine the frequency range of the signal in the application. Different shunts have different performance over different frequency ranges; determines whether the signal is analog or digital. This affects the choice of shunt; determine the power level of the input signal and the power requirements of the output signal, and select the appropriate shunt that can handle the required power.

5. Understand the signal loss of the shunt. In some applications, low signal loss can be a critical factor.

6. Make sure the input and output port impedance of the shunt matches your system or circuit to reduce problems caused by reflections and signal mismatch.

Ⅳ. The main function of the shunt

1. Experiments and tests: Shunts can be used in laboratories and test environments to distribute test signals to different test equipment for different types of tests.

2. Signal distribution: One of the main functions of the splitter is to distribute an input signal to multiple output ports, so that multiple devices or circuits receive the same signal respectively.

3. Signal analysis: The shunt enables the user to transmit the input signal to multiple analysis instruments or test equipment at the same time for multi-angle signal analysis and detection.

4. Signal sharing: share a signal source between multiple devices or multiple circuits to ensure that they get the same input signal at the same time for synchronous operation.

5. Multiplexing: Splitters play a key role in multiplexing systems, helping to transmit multiple input signals to different target devices through a shared transmission medium.

6. Signal monitoring: By shunting the input signal to different analysis devices, the signal can be monitored, analyzed and recorded in real time.

7. Phase maintenance: In some applications, shunts are used to ensure that the phases of multiple branch outputs are consistent, such as in radio frequency and radar systems.

8. Radio frequency and communication systems: In radio frequency and communication systems, splitters are used to distribute signals to multiple antennas in order to achieve extended signal coverage.

Ⅴ. Types and functions of shunts

1. Network splitter

To be precise, it is a crossed network cable. Generally, the network splitter has only a few holes, one side is for plugging in the network cable, and the other side is for connecting to the computer network cable. It is usually a rectangular box with three to four ports on the outside.

2. General shunt

It is used to measure DC current, and it is made according to the principle that when DC current passes through a resistor, a voltage is generated at both ends of the resistor. Shunts are widely used to expand the measuring current range of instruments. There are fixed fixed-value shunts and precision alloy resistors, which can be used for current limiting and current sampling detection in communication systems, electronic complete machines, and automatic control power supplies.

3. Wire shunt

Wire shunts are now the first choice for electrical designers in various design institutes. This is mainly because the product is a national patent product. The conductor material selected for the product is copper after molding and then tinned, which ensures that the material selected for the product is the same as the cable conductor. , The connection of the conductor is surface contact, and the protection level of the product reaches IP63. Wire shunt products have a complete coverage and a variety of specifications and models, which can fully meet the power distribution methods in various situations.

4. Equalizer

The input power is evenly distributed to multiple output ports, and each output port gets the same power. Splitters are commonly found in communications and RF applications.

Ⅵ. Design and construction of the shunt

1. Distribution network: The core of the splitter is the distribution network, which distributes the input signal to multiple output ports. The distribution network can adopt various circuit topologies, such as microstrip lines, transmission lines, couplers, etc.

2. Encapsulation: Shunts are usually encapsulated to protect internal circuitry, reduce interference, and provide proper connection.

3. Output port: A shunt usually has two or more output ports, each connected to a different device or circuit.

4. Input port: The splitter has an input port that receives the input signal and then distributes it to each output port.

5. Phase balance: In some applications, phase balance is important to the performance of the shunt. Therefore, special circuit design may be required to achieve phase balance in the design.

6. Impedance matching: The input and output ports of the shunt usually need to consider impedance matching to reduce the problems caused by signal reflection and mismatch.

7. Signal loss: The design of the shunt should consider the minimization of signal loss to ensure the quality of the output signal.

8. Material selection: The material used to make the shunt needs to have good electrical properties, insulation properties and durability.

VII. The Role of Shunts in Electronic Test and Measurement

1. Signal distribution and sharing: The input signal is shared between test equipment, so that multiple test instruments can test and analyze the same signal at the same time.

2. Radio frequency and microwave system testing: In high frequency and microwave systems, splitters are used to distribute signals to multiple antennas or devices to test radio frequency performance and transmission characteristics.

3. Multi-channel test: The shunt allows the input signal to be distributed to multiple channels, and different parameters are tested on each channel, so that multiple tests can be performed at the same time.

4. Synchronous measurement: Distribute the input signal to multiple measurement devices to ensure that they measure the same signal at the same time, thereby achieving data synchronization.

5. Spectrum analysis: Distribute the input signal to multiple spectrum analyzers to monitor signals in different frequency ranges at the same time.

6. Network analysis: In the field of radio frequency and microwave, shunts are used to transmit test signals to network analyzers to measure network parameters such as S parameters and reflection coefficients.

7. Circuit characteristic test: Distribute the signal to different circuits to measure its characteristics, such as amplitude response, phase response, frequency response, etc.

8. Noise analysis: By distributing the signal to multiple noise analyzers, the noise level in different frequency ranges can be measured simultaneously.

Ⅷ. Application of shunt

1. Shunt as circuit protection

When a circuit must be protected from overvoltages and there are failure modes in the power supply that could produce such overvoltages, the circuits can be protected by devices commonly known as crowbar circuits.

When this device detects an overvoltage, it causes a short circuit between the power supply and its loop. This will result in an immediate drop in voltage (to protect the device) and a momentary high current, which is expected to open a current sensitive device (such as a fuse or circuit breaker). The device is called a crowbar because it resembles throwing an actual crowbar across a set of bus bars (exposed electrical conductors).

2. Diodes as shunts

If a device is susceptible to signal or power reverse polarity, a diode can be used to protect the circuit. If connected in series with the circuit, it just prevents reverse current, but if connected in parallel, it can shunt reverse power, causing a fuse or other current limiting circuit to open.

All semiconductor diodes have a threshold voltage (usually between 0.5 volts and 1 volt) that must be exceeded for high currents to flow through the diode in the normally permissible direction. Two anti-parallel shunt diodes (one conducting current in each direction) can be used to limit the signal flowing through them to not exceed their threshold voltage to protect subsequent components from overloading.

3. For current measurement

Ammeter shunts can measure current values that are too large to be measured directly by a particular ammeter. In this case, a separate shunt (a resistor of very low but accurately known resistance) is placed in parallel with the voltmeter so that nearly all the current to be measured will flow through the shunt (assuming the voltmeter's internal resistance is negligible as a fraction of the current).

Choose the resistors so that the resulting voltage drop is measurable, but low enough not to destroy the circuit. The voltage across the shunt is proportional to the current flowing through it, so the measured voltage can be scaled to directly display the current value.
The shunt rating is determined by the maximum current and the voltage drop at that current. For example, a 500 A, 75 mV shunt has a resistance of 150 microohms and a maximum allowable current of 500 amps, at which current the voltage drop will be 75 millivolts.

If the current being measured is also at a high voltage potential, that voltage will also be present in the connecting leads and in the reading instrument itself. Sometimes a shunt is plugged into the return leg (ground side) to avoid this problem. Some alternatives to shunts can provide isolation from high voltage by not connecting the meter directly to the high voltage circuit. Examples of devices that can provide this isolation include Hall-effect current sensors and current transformers.

If one side of the circuit is grounded, a current measurement shunt can be inserted into the ungrounded or grounded conductor. Shunts in ungrounded conductors must be insulated to ensure full circuit voltage ground; measuring instruments must be intrinsically isolated from ground, or must include a resistive divider or isolation between the relatively high common-mode voltage and the lower voltage inside the instrument amplifier. A shunt in the ground conductor may not be able to detect leakage currents bypassing the shunt, but it will not experience high common-mode voltages to ground.


Frequently Asked Questions

1、What is the difference between a shunt and a circuit breaker?
A shunt trip breaker is an optional accessory for your circuit breaker that can allow you to trip the breaker remotely at any time or automatically during a surge, preventing injuries and equipment damage during emergencies.
2、What is a shunt in a substation?
Shunt reactors provide voltage control and reactive power compensation. They are arranged between line voltage and ground. Their place of installation is usually located at the start or end of a long overhead power line or cable connection, or in central substations.
3、Is a shunt the same as a resistor?
In the past, a resistor connected in parallel to an ammeter as a shunt to expand the current measurement range is called a shunt resistors, but in recent years resistors used to detect circuit current are collectively referred to as shunt resistors (current sense shunt resistor).
4、What is the meaning of shunt in electrical?
A shunt is an electrical device that generates a low-resistance path for an electrical current. This enables the current to flow to an alternative point in the circuit. Shunts may also be referred to as ammeter shunts or current shunt resistors.

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