(2) Code for Design of Automatic Fire Alarm System (GBJ/ 16-88), the national standard of People's Republic of China (PRC). ⑴ Transmission mode: The output power of the system is fed by wired broadcast transmission mode.
⑵ Line attenuation requirements: In the public broadcasting system, the line attenuation output by power amplifier equipment to the farthest user speaker on the line shall meet the following requirements: business broadcasting shall not be greater than 2 dB (at 1kHz) and business broadcasting shall not be greater than 1 dB (at 1kHz).
⑶ Feed circuit with constant voltage output is adopted, and the output voltage is 70V or 100V.
(4) Calculation method of power amplifier capacity:
Service broadcasting system and calculation method of service broadcasting system;
p = k 1×K2×σPo
Where: p- the total electric power output by the power amplifier (W);
Po-Ki×Pi, the maximum electric power (w) when each branch broadcasts at the same time;
Pi-the rated capacity of the user equipment in the i-th branch;
Ki-I simultaneous shunt demand coefficient;
For service broadcasting, the Ki of each room program is 0.2-0.4;
The background music program Ki is 0.7-0.8.
K 1-line attenuation compensation coefficient:1.26 when the line attenuation is 1dB; 1.58 when the line attenuation is 2dB;
K2—— aging coefficient, generally1.2-1.4;
Calculation method of fire accident broadcasting system: There are two calculation methods for this system:
The capacity of a power amplifier is determined by 1.3 times of the total number of speakers in the system.
The capacity of B power amplifier is determined by 1.5 times of the total number of the largest three-layer speakers in the system.
5] Standby of power amplifier
The power amplifier of public address system should be equipped with standby power amplifier, which can be put into use automatically or manually when the working power amplifier fails. The standby power amplifier of important broadcasting power amplifier (such as fire accident broadcasting power amplifier) should be able to be put into use automatically when the working power amplifier fails. The number of standby power amplifiers should be determined according to the capacity of important broadcast loads.
[6] Speaker Settings
The office, living room and dressing room are equipped with 3W speakers.
Floor corridors generally use ceiling speakers, and the speaker spacing is about 2.5 times of the floor height (ceiling height). Choose 3-5W ceiling speakers.
3-6W speakers should be installed in halls, general meeting rooms, restaurants, shopping malls and entertainment places.
The bedside control cabinet in the guest room uses 1W-2W speakers.
When the building decoration and the clear height of the room allow, sound columns or combined speakers should be used in places with large space.
When setting speakers in places with high noise and humidity, speakers should be used. The sound pressure level of horn speakers used in high noise places should be higher than the ambient noise 10- 15 dB.
Once the power requirements of broadcasting system
Small-capacity radio stations can supply power directly from sockets; When the capacity is above 500W, a broadcast control room is set, and its power supply can be supplied by the nearest power controller line.
In general, the AC voltage offset value should not be greater than+10%. When the voltage offset cannot meet the limit requirements of the equipment, an automatic voltage regulator should be installed near the equipment.
The capacity of AC power supply for broadcasting is generally 0.5-2 times of the AC power consumption of 65438+ final broadcasting equipment.
Fire accident broadcasting equipment adopts fire power supply.
As a choice of transmission cable.
Room service broadcasting line should use copper core multi-core cable or copper core plastic stranded wire.
Other broadcasting lines should use copper-core plastic stranded wire.
Shielded wires should be used for all kinds of program signal wires.
Fire accident broadcasting lines should use flame-retardant copper core cables or fire-resistant copper core wires and cables.
Levies line laying mode
Lines shall be laid through steel pipes or trunking, and shall not be laid in the same trunking as lighting and power lines.
Fire prevention measures should be taken for fire accident broadcasting lines. (1) The setting of fire accident broadcast speakers shall meet the following requirements:
Emergency broadcast speakers should be installed in public places such as walkways, halls and restaurants, and the last speaker at the end of the walkways should be no more than 12m away from the wall. The rated power of each speaker should not be less than 3W.
The speaker power in the guest room shall not be less than1w.
Speakers with background noise, such as air conditioning rooms, ventilation rooms, laundry rooms, entertainment places and parking garages, should have the farthest sound pressure level higher than the background noise by 15 dB, so as to determine the power of the speakers.
⑵ The feeder voltage of fire accident broadcasting shall not be greater than100V .. Each floor shall be provided with feeder isolation voltage devices to ensure that the normal broadcasting of other branches will not be affected when any branch fails.
(3) The fire accident broadcast output shunt should be controlled according to the evacuation sequence, and the floor control program for playing evacuation instructions is as follows:
In case of fire on floors above N, the upper and lower floors adjacent to the fire floor should be connected first.
When there is a fire on the first floor, the first floor, the second floor and the underground floors should be connected.
If there is a fire in the basement, the underground floors and the first floor should be connected first.
(4) When fire accident broadcasting is combined with service broadcasting or commercial broadcasting, the following requirements shall be met:
In case of fire, the loudspeaker and the corresponding power amplifier on the fire evacuation floor should be able to enter the fire accident broadcasting state in the fire control room.
The fire control room should be able to monitor the working state of the fire accident broadcast power amplifier.
Speakers should be installed on the bedside table of the guest room, and the speakers should have the function of fire broadcasting.
If the speakers used for fire accident broadcasting, service broadcasting or commercial broadcasting have volume switches, the system should use three-wire wiring to forcibly turn on the fire accident broadcasting.
Public broadcasting is a kind of broadcasting that serves the public in a limited scope. In general, public broadcast signals are transmitted through the broadcast lines arranged in the broadcast service area, which is one-way (downlink) wired broadcast. Usually set in communities, institutions, military units, enterprises, schools, buildings, supermarkets and various places, it is used to release news and internal information, release work and rest signals, provide background music, page and forcibly insert emergency broadcasts of catastrophic accidents. Therefore, it has become an indispensable part of various public places in urban and rural areas and modern cities. I believe that in the 9. 1 1 incident that shocked the world, its public address system must have played an important role in saving lives before the collapse of the World Trade Center. Design requirements of public broadcasting: (1) transmission mode: the output power of the system is fed by wired broadcasting. ⑵ Line attenuation requirements: In the public broadcasting system, the line attenuation output by power amplifier equipment to the farthest user speaker on the line shall meet the following requirements: business broadcasting shall not be greater than 2 dB (at 1kHz) and business broadcasting shall not be greater than 1 dB (at1kHz); ⑵ Feeder with constant voltage output should be adopted, and the output voltage should be 70V or 65438. ⑷ Calculation method of power amplifier capacity: commercial broadcasting system and commercial broadcasting system: p = K 1× K2× σ Po, where: p- total output power of power amplifier (w); Po-Ki×Pi, the maximum electric power (w) when each branch broadcasts at the same time; Pi-the rated capacity of the user equipment in the i-th branch; Ki-I simultaneous shunt demand coefficient; For service broadcasting, the Ki of each room program is 0.2-0.4; The background music program Ki takes 0.7-0.8k 1 line attenuation compensation coefficient: line attenuation1dbh1.26; 1.58 when the line attenuation is 2dB; K2—— aging coefficient, generally1.2-1.4; Calculation method of fire accident broadcasting system: There are two calculation methods for the system: a. The capacity of power amplifier is determined according to 1.3 times of the total number of speakers in the system. The capacity of power amplifier B is determined by 1.5 times of the total number of the largest three-layer speakers in the system. 5] standby power amplifier The power amplifier of the public address system should be equipped with standby power amplifier, which can be put into use automatically or manually when the working power amplifier fails. The standby power amplifier of important broadcasting power amplifier (such as fire accident broadcasting power amplifier) should be able to be put into use automatically when the working power amplifier fails. The number of standby power amplifiers should be determined according to the capacity of important broadcast loads. [6] Speaker setting: 3W speakers are set in the office, living room and dressing room. Floor corridors generally use ceiling speakers, and the speaker spacing is about 2.5 times of the floor height (ceiling height). Choose 3-5W ceiling speakers. 3-6W speakers should be installed in halls, general meeting rooms, restaurants, shopping malls and entertainment places. The bedside control cabinet in the guest room uses 1W-2W speakers. When the building decoration and the clear height of the room allow, sound columns or combined speakers should be used in large space places. When setting speakers in places with high noise and humidity, speakers should be used. The sound pressure level of horn speakers used in high noise places should be higher than the ambient noise 10- 15dB. (7) The power supply of broadcasting system requires that small-capacity broadcasting stations can be directly powered by sockets; When the capacity is above 500W, a broadcast control room is set, and its power supply can be supplied by the nearest power controller line. In general, the AC voltage offset value should not be greater than+10%. When the voltage offset cannot meet the limit requirements of the equipment, an automatic voltage regulator should be installed near the equipment. The capacity of AC power supply for broadcasting is generally 0.5-2 times of the AC power consumption of 65438+ final broadcasting equipment. Fire accident broadcasting equipment adopts fire power supply. ⑻ Selection of transmission cable The service broadcasting line in the guest room should adopt copper-core multi-core cable or copper-core plastic stranded wire. Other broadcasting lines should use copper-core plastic stranded wire. Shielded wires should be used for all kinds of program signal wires. Fire accident broadcasting lines should use flame-retardant copper core cables or fire-resistant copper core wires and cables. (9) Line laying mode The line shall be laid through steel pipes or trunking, and shall not be laid through trunking together with lighting and power lines. Fire prevention measures should be taken for fire accident broadcasting lines.