|
The Emergency Light Manufacturers stated that the emergency lighting system is mainly controlled by its own power supply. The normal power supply is connected to the normal lighting power supply circuit. The emergency light battery is charged normally. When the normal power supply is cut off, the backup power supply (battery) is automatically powered. This type of emergency light has a large number of electronic components such as transformer, voltage regulator, charging, inverter, battery, etc. inside the lamp. The battery needs to be charged and discharged during use, maintenance and failure. The other is centralized power supply centralized control type. There is no independent power supply in the emergency light fixture. When the normal lighting power supply fails, the centralized power supply system supplies power. In this form of emergency lighting system, the complicated electronic circuits inside all the lamps are omitted. The emergency lighting fixtures are no different from ordinary lamps, and the centralized power supply system is set in a dedicated room. Its circuit is shown in Figure 1. Here's how it works. When the power supply is normal, J2 (polyelectric) is electrically connected, its moving contact is connected with "N/O (normally open)", and the positive end of the backup battery is connected with the inverting end of IC1. IC1 (LM308) and D5, D6 form a voltage comparator, and the reference voltage is determined by D5 and D6. Here, a silicon diode (D5) and a 6.2V Zener diode (D6) are used to form a reference voltage of 6.9V to monitor the charging voltage. When IC1's 2-pin input voltage (both battery voltage) is lower than 6.9V, IC1's 6-pin output is high, T1 is turned on, J1 (polyelectric) is powered, and its moving contact is "N/O (often The switch is turned "on", the power supply voltage is charged to the battery through R2, and the LED2 is lit as the charging indication. Change the R2 resistance to adjust the charging current. As the charging time increases, the voltage of pin 2 of IC1 gradually increases. When the voltage is greater than the reference voltage of 6.9V, the 6 pin of IC1 outputs a low level, T1 is cut off, J1 (polyelectric) loses power, and the charging circuit is disconnected to realize automatic Charging protection.
When the power is cut off, J2 (polyelectric appliance) loses power, its moving contact is connected with "N/C (normally closed point)", and the battery supplies power to the emergency light circuit through S1, which realizes the automatic switching function during power failure. S1 is used here to manually cut off the emergency light circuit section. The emergency light circuit is composed of IC2 (NE555), T2, T3, T4, X2 and the like. IC2 constitutes a 50Hz signal generator, and 50Hz signal is output from the 3rd pin of IC2. The push-pull circuit consisting of T3, T4 and X2 is respectively driven by T2 inversion and amplification, and 220V AC is induced on the high voltage side of X2 to make the fluorescent tube Light up. The X2 here can directly use the finished power transformer with a secondary voltage of 4.5 volts and a primary 220V, depending on the power of the power test fluorescent tube. When using, pay attention to T3, T4 should be added radiator.
At the time of production, X1 uses a power transformer with a secondary 6V/200mA. J1, J (Polymer) 2 selects a relay with a coil voltage of 6V. Other device options can be found in the illustration, no special requirements. The circuit debugging is very simple. When the main power is turned on, J2 (poly) should be activated, and LED1 is the power indication. Then measure whether the voltage of pin 3 of IC1 is about 6.9V. Then, an external power supply can be used to access the IC2 pin to adjust the charging protection circuit. When the input voltage is greater than 6.9V, J1 should be disconnected. Short open S1, use external power supply to connect to the emergency light circuit, measure whether the output of IC2 is 50Hz, and then measure whether the voltage of X2 output part is about 220V. LED3 is an indication of power failure/emergency light operation.
https://www.linsheng.com
|
|
