Kiloamp Technology - The Global Provider of Electronic Security Protection
Kiloamp 2018-08-28 539
Design Basis
GB50057-2010 "Building Lightning Protection Design Code"
GB50343-2004 "Building Electronic Information System Lightning Protection Technical Specifications"
QX3-2000 "Weather Information System Lightning Strike Electromagnetic Pulse Protection Specification"
GB18802 "Surge Protector (SPD) for Low Voltage Distribution System"
IEC61312-1, 2, 3 "Protection of Lightning Electromagnetic Pulses"
GB50169-92 "Code for Construction and Acceptance of Grounding Device for Installation of Electrical Installations"
GB50194-93 "Safety Specifications for Power Supply and Use at Construction Sites"
YD/T 5098-2001 "Communication Bureau (Station) Lightning Overvoltage Protection Engineering Design Specification"
In order to strengthen and standardize the lightning protection work of the secondary system, reduce the harm of lightning to the secondary system (automation, computer, communication, protection and other weak electrical equipment), and ensure the safe, stable and reliable operation of the power grid, this plan is formulated.
The secondary system of the power grid company refers to the auxiliary equipment in the substation and in the communication and dispatching building protection system, automation system, communication system, computer network equipment and monitoring system, power system, air conditioner and so on.
First, the power system
1. After the low-voltage power cable is introduced into the equipment room, when the power supply system adopts the TN-S mode, in the AC voltage regulator or the AC power distribution panel (box), the phase line and the neutral line should be respectively installed with the pressure-limiting SPD. When the power supply system adopts the TN-CS mode, after the low-voltage power cable is introduced into the equipment room, the phase line should be separately installed with the voltage-limiting SPD in the AC voltage regulator or the AC power distribution panel (box).
Install Kiloamp I-class power surge protector KPA385-2531R, 25kA (10/350μs), or Kiloamp power lightning protection box KPF385-12031R, 120kA (8/20μs), can be tens of thousands or even hundreds of thousands of volts The overvoltage is limited to several kilovolts, and the lightning arrester is installed in parallel at the incoming end of the main power distribution room to protect the lightning strike and the conducted lightning.
2. When the power distribution system of the substation is powered by the main distribution room and the distribution room, if the length of the low-voltage buried cable between the total distribution screen and the distribution screen is greater than 50m, the distribution screen cable should be distributed. A voltage-limiting SPD with a nominal discharge current of not less than 40kA is installed on the input side.
Here, the Kiloamp III-level power surge protector KPB385-4040R, 40kA (8/20μs) is installed, which can effectively limit the residual voltage within kilovolts. This level of lightning protection device is installed in parallel, and the power of the subsequent equipment is not limited.
3. If the length of the power cable between the power distribution panel and each layer of distribution box exceeds 30m or the length of the power cable does not exceed 30m, but the power supply of the control terminal and network equipment and instrument of this layer is sensitive to lightning, the distribution box The internal power supply core should be installed with a voltage limiting SPD with a nominal discharge current of not less than 20kA.
Install Kiloamp Class III power surge protector KPB385-2040R, 20kA (8/20μs), which can effectively limit the residual voltage within kilovolts. This class of lightning arresters is installed in parallel, and the power of the connected devices is not limited.
5. The DC power supply SPD with a nominal discharge current of not less than 10kA should be installed at the DC feeder end of the DC power distribution panel in the substation.
6. The power distribution screen of the equipment room, the power distribution screen of the UPS special equipment, etc., according to the actual situation, install the pressure limiting SPD with the nominal discharge current not less than 20kA.
Install Kiloamp Class III power surge protector KPB385-2040R, 20kA (8/20μs), which can effectively limit the residual voltage within kilovolts. This class of lightning arresters is installed in parallel, and the power of the connected devices is not limited.
Precautions:
1. A lightning arrester should be installed on the low voltage side of the distribution transformer. The grounding terminal of the arrester should be grounded to the outer casing of the transformer, the neutral conductor and the armor layer of the power cable.
2. The low-voltage power cable entering the substation room should be led by cable trench or by cable with metal sheath or directly through metal pipe. The length of the metal pipe should not be less than 15m.
3. When the upper-level SPD and the secondary SPD adopt the voltage-limiting SPD, the cable length between the two should be greater than 5m.
4. Lightning overvoltage protection design of substation DC power line
(1) When the connection cable of the DC screen and the split screen is greater than 50 meters, a suitable DC SPD should be installed at the incoming end of the feeder entering the split screen.
(2) The SPD used in the DC power supply system in the substation shall have a fuse function, the nominal discharge current shall not be less than 10kA, and the SPD shall be grounded nearby.
Second, the signal system
1. Before the high-frequency cable of the multiplexed carrier channel enters the carrier device, the high-frequency signal SPD with a nominal discharge current of not less than 10kA (8/20μs) should be installed. From the protection screen, AC power screen, DC power screen, measurement screen, etc. to the monitoring communication line of the total control panel, if the length exceeds 30 meters, the corresponding nominal discharge current should be installed within the total control panel of not less than 5kA (8/20μs). Signal SPD.
The Kiloamp Control Signal Surge Protector, KSC12-201, 10kA (8/20μs) should be installed here.
2. When the audio cable (or data cable) of the carrier and microwave output is longer than 30 meters, the Kiloamp audio signal SPD with a nominal discharge current of not less than 5kA (8/20μs) should be installed at the carrier and microwave distribution frame. The Kiloamp audio signal lightning arrester, KSA180-201, 5kA (8/20μs) should be installed here.
Precautions:
1. The carrier high-frequency cable entering the main control or communication equipment room must be grounded in the screen and combined with the filter.
2. The various signal lines of the high-voltage site to each room in the station and the various signal lines between different buildings in the station should be optical fiber or shielded cable. The shielding layer of the shielded cable should be grounded at both ends. The vacant core wire of the cable should be at both ends. Ground.
3. When the vertical length of the signal line is greater than 30m, the metal pipe should be worn, and both ends of the metal pipe must be welded to the equalizing net or the grounding net of the floor.
4. For the communication connection lines of different systems, the corresponding signal SPD or opto-isolator with nominal discharge current not less than 5kA (8/20μs) should be installed at one or both ends of its line according to actual conditions.
Third, microwave communication system
The waveguide feeder and the outer sheath of the coaxial cable erected on the iron tower shall be grounded at the upper and lower ends and the outside of the entrance to the equipment room respectively. When the length of the feeder and coaxial cable is greater than 60m, the shielding layer should be increased in the middle of the tower. A ground connection point, both ends of the outdoor cable tray should be grounded.
When the feeder of the microwave station adopts coaxial cable, a coaxial SPD with a nominal discharge current of not less than 10kA shall be installed at the entrance of the coaxial cable to the machine room. The grounding lead of the coaxial SPD grounding terminal shall be from the grounding wire outside the inlet of the antenna feeder. , lightning protection belt or ground grid connection.
The Kiloamp feeder lightning arrester KAG70-25NFM, 20kA (8/20μs), should be installed here.
Fourth, substation secondary system grounding requirements
1. The grounding method of the secondary system of the power grid should adopt the common grounding. When the communication station is more than 15 meters away from the edge of the substation grounding grid, a special grounding grid shall be provided.
2. When there is power and communication cable connection between buildings adjacent to each other, the grounding devices should be connected to each other.
3. The computer room should not be located on the top floor of the building. If the machine room is located on the top floor of the building, the machine room should be shielded and decorated.
4. The metal pipe entering and leaving the machine room should be buried more than 10 meters before being introduced into the room, and the equipotential connection should be made near the ground at the entrance.
5. If the wires introduced into the equipment room are not used temporarily, they should be grounded on the distribution frame to prevent the introduction of direct lightning strikes and inductive lightning to counterattack at the end of the open wire.
6. Metal objects such as pipes, structures, shafts, and corridor cable supports should be grounded every 20 meters.
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