What are the specifications of the power cord

A power line is a wire that carries current. Generally, the mode of current transmission is point-to-point transmission. Power lines can be divided into AC AC power lines and DC DC power lines according to their purposes. Generally, AC power lines are wires with high voltage of AC power. Such wires can be formally produced only after they have obtained safety certification according to unified standards due to high voltage. The DC line basically passes through DC with low voltage, so the safety requirements are not as strict as AC line. However, for safety reasons, countries still require unified safety certification.
Performance index of twisted pair in power line
For twisted pair, users are most concerned about several indicators that characterize its performance. These indicators include attenuation, near-end crosstalk, impedance characteristics, distributed capacitance, DC resistance, etc.
(1) Attenuation
Attenuation is a measure of signal loss along the link. Attenuation is related to the length of the cable. As the length increases, the signal attenuation also increases. The unit of attenuation is "db", which represents the ratio of signal strength from the source transmitter to the receiver. Since attenuation varies with frequency, the attenuation shall be measured at all frequencies within the application range.
(2) Near-end crosstalk
Crosstalk is divided into near-end crosstalk and far-end crosstalk (FEXT). The tester mainly measures NEXT. Because of the line loss, the magnitude of FEXT has little impact. Near-end crosstalk (NEXT) loss is the measurement of signal coupling from one pair of lines to another in a UTP link. For UTP links, NEXT is a key performance indicator and also an indicator that Z is difficult to measure accurately. With the increase of signal frequency, its measurement difficulty will increase. NEXT does not represent the crosstalk value generated at the near end point, it only represents the crosstalk value measured at the near end point. This value will vary with the length of the cable. The longer the cable, the smaller the value. At the same time, the signal at the sending end will also be attenuated, and the crosstalk to other line pairs will also be relatively small. Experiments have proved that only the NEXT measured within 40 meters is more real. If the other end is an information socket that is more than 40 meters away, it will produce a certain degree of crosstalk, but the tester may not be able to measure this crosstalk value. Therefore, it is better to measure NEXT at both ends. The current testers are equipped with corresponding equipment, so that the NEXT values at both ends can be measured at one end of the link.
(3) DC resistance
TSB67 does not have this parameter. The DC loop resistance consumes part of the signal and converts it into heat. It refers to the sum of the resistance of a pair of wires,
The DC resistance of twisted pair of 11801 specification shall not be greater than 19.2 Ohms. The difference between each pair should not be too large (less than 0.1 ohm), otherwise it means poor contact, and the connection point must be checked.
(4) Characteristic impedance
Unlike the loop DC resistance, the characteristic impedance includes the resistance and the inductive impedance and capacitive impedance with frequency of 1~100MHz. It is related to the distance between a pair of wires and the electrical performance of the insulator.
Various cables have different characteristic impedances, while twisted pair cables have 100 ohms, 120 ohms and 150 ohms.
(5) Attenuation Crosstalk Ratio (ACR)
In some frequency ranges, the ratio between crosstalk and attenuation is another important parameter reflecting the cable performance. ACR is sometimes expressed as signal-to-noise ratio (SNR),
It is calculated by the difference between the attenuation of Z difference and the NEXT value. A large ACR value indicates a stronger anti-interference ability. General system requirements shall be at least greater than 10 dB.
(6) Cable characteristics
The quality of the communication channel is described by its cable characteristics. SNR is a measure of data signal strength in consideration of interference signals. If SNR is too low,
When the data signal is received, the receiver cannot distinguish the data signal from the noise signal, and Z will eventually cause data error. Therefore, in order to limit data errors to a certain range,
A minimum acceptable SNR must be defined.
The commonly used wire specifications for home decoration include: 1, 1.5, 2.5, 4, 6, 10, 16, 25, 35, 50, 70, 95, 120, 150, 185, 240, 300, 400 and 500 square millimeters.
In addition: such as
VV4X16MM2 is a PVC insulated and PVC sheathed copper core cable with 4 cores and 16 square meters per core.
BV1X95MM is a PVC insulated copper core wire with a section of 95m2.
RVV3X2.5MM2 -- general R added at the back represents "multi-core flexible wire", and the front is generally "ZR", representing flame retardant.
VV is PVC insulated and PVC sheathed cable,
BV is a flat PVC sheathed cable,
RVV is PVC insulated and PVC sheathed flexible cable.
The following represents the cross-sectional area of several copper wires.
Generally, the copper core wire can pass 4~6A current at 1 mm2, that is, 1 mm2 can pass 5A current, that is, 1.1 kW, and so on; Generally, 2.5 is used for the air conditioner, 4 for the cabinet, and 1 for the lighting.