100 Questions About Video Surveillance, Come and Get It! (4)

61. How to choose a power cord in the centralized power supply?

The power cord is required to use an outdoor waterproof cord of 1.5 square meters or more.

62. Why choose a centralized power supply in the monitoring system?

A: It is convenient for the unified control of the power supply of the monitoring system.

B: It is conducive to the protection of power supply lightning protection.

C: It is convenient to uniformly supply power to the monitoring system through a regulated power supply.

63. What are the requirements for connecting the power cord and sealing in the centralized power supply?

A: Welding the power cord connector.

B: Use thin heat shrinkable tubing to insulate the outside of the joint.

C: Use hot melt to waterproof and seal the joint, and put on a heat-shrinkable tube.

D: Heat to melt the silica gel and shrink the heat-shrinkable tube.

64. What tools are required for connecting and sealing power cords in the centralized power supply?

A: Electric soldering iron

B: Solder

C: Heat-shrinkable tube

D: Hot melt silica gel

E: Hot air gun

F: Wire stripping pliers

65. How to choose the wiring route during the wiring process of the server-side monitoring system?

The server-side engineering wiring can adopt a combination of series, star, and series of stars.

66. How shall we lay lines in the server-side monitoring system?

A: Laying along the wall

B: Laying overhead

C: Laying underground

67. What are the requirements of the server-side monitoring system for AC power supply?

A: The power supply of the hard disk video recorder requires an AC voltage of 220V±5%.

B: The AC voltage required for the power supply of the AV controller, control host, and monitoring sub-machine is +85V ~ +265V.

68. What is the role of the ground wire?

A: Functional grounding is to ensure the normal operation of electrical equipment or the low-noise grounding of electrical systems.

Mainly divided into center point grounding, working grounding, logic grounding, shielding grounding.

B: Protective grounding is to prevent people or equipment from being injured or killed by electric shock

Mainly divided into shell protective grounding, building grounding, lightning protection grounding, electrostatic grounding, repeated grounding

69. What materials are needed to make the ground wire?

A: Galvanized steel pipe

B: Expansion bolt

C: Galvanized steel strip

D: Copper nose

E: 10 square copper wire

70. What factors affect the resistance value of the ground wire?

A: The salinity of the soil.

B: The humidity of the soil.

C: The number and spacing of ground steel pipes.

71. How to reduce the ground resistance of the ground wire by improving the soil quality around the ground wire? What materials are needed?

Saltwater, charcoal powder, and other materials are needed. Inject saltwater, charcoal powder, etc. into the ground pit.

72. What is the system's requirement for ground wire resistance?

The size, connection method, and the relationship between the grounding resistance of the DC working should be determined according to the requirements of different electronic devices, and it is generally required that the resistance should not be greater than 4Ω.

A: The grounding resistance of the safety grounding should not be greater than 4Ω.

B: The grounding resistance of the safe working ground should not be greater than 4Ω.

C: The grounding resistance of lightning protection grounding should not be greater than 10Ω.

73. What are the hazards of harsh weather such as thunder and lightning to the server-side monitoring system？

A: Interference with video signals, audio signals, and data communications.

B: Damage to the monitoring equipment.

74. How does the lightning protection module work?

When high current and high voltage enter the input terminal of the lightning protection module, the lightning protection module opens the circuit between the input and output, and the lightning protection module leads the high voltage and high current to the earth through the ground wire.

75. How to install the lightning protection module?

Install it at the forefront of electrical equipment.

76. What are the lightning protection circuit design and components adopted by the video and audio controller (monitoring host) in the video, audio, communication, and power supply?

A: Lightning protection diode

B: Varistor

C: Self-recovery fuse

D: Inductance

The transient suppression diode can absorb 400W-600W power instantly and can absorb tens of thousands of volts in a few microseconds.

77. What are the advantages of the modular power supply used in the power circuit of the video and audio controller (monitoring host, monitoring sub-computer)?

When the power supply voltage fluctuates (AC85～AC265), ensure that the equipment can work normally without being affected.

78. What are the working steps of a modem?

A: Send a serial binary digital signal from the hard disk video recorder.

B: Convert these binary data into analog signals through MODEM.

C: Send the analog signal to the telephone line.

D: The analog signal is converted into a binary digital signal by MODEM.

E: The hard disk video recorder receives binary digital signals.

79. What is the data transmission mode of the hard disk video recorder?

A: Serial transmission method

B: Parallel transmission method

80. What is the classification of interference?

A: External interference

B: Internal system interference