From the definition of IEC, EPS is functionally consistent with the definition of standby UPS, that is, when the utility power is normal, the mains supply to the load; when the utility power fails, the battery provides energy, inverse The transformer supplies power to the load. However, some people say that EPS is a backup UPS, this argument is not scientific, devalued the important role of EPS itself. As we all know, the commonly used standby UPS is generally of low power, and most of the protection objects are PCs (ie, rectified and filtered loads). Because the object of protection does not involve personal safety and key equipment, and the market demand is large, the technical content is low (the single load does not require high waveforms), the price competition is fierce, and low-end goods are more, resulting in low product quality and large repair rate. Give people a bad impression, think that standby UPS is optional PC peripherals, only equivalent to the power strip. The EPS is an emergency fire-fighting power supply. The emphasis is on firefighting emergency. It is truly a device that “has a thousand troops for a day and uses a soldier for a while†in order to truly provide emergency power.
1 EPS topology design EPS machine reliability (MTBF) is not a simple combination of basic units. In order to meet the reliability of the entire machine, how to configure the reliability of each basic unit is crucial. In order to ensure the reliability of the whole machine (especially from personal safety and fire escape), the MTBF of the EPS consists of the charger MTBF, the MTBF of the inverter, the MTBF of the low-voltage electrical appliances, and the MTBF of the control unit. It can be seen that the MTBF of the complete machine is formed by the superposition of the MTBF of the major components. Therefore, the overall design of the EPS requires a detailed study, analysis, and calculation of the MTBF of each major component to improve the MTBF of the weak components because the MTBF of the weak component is determined. The MTBF of the whole machine, therefore, needs to configure the security life cycle of each major component from the needs of the overall security life cycle of the EPS.
2 Difference between EPS and UPS EPS is developed from the application of UPS. This sentence is not exact. Because the transfer function of the EPS and UPS core component inverter control system is completely different, it is reflected in the EPS load power factor, load capacity, overload multiple, short-circuit protection of the output circuit, the mandatory operation of the inverter and other parameters and Performance is much better than UPS. General UPS can be used as a voltage closed loop system, while EPS is a multi-closed loop system with current inner loop (as shown in Figure 2), which is the key to EPS. In addition, their related protection is completely different.
(1) The development of EPS in China originated from fire alarms and unexpected failures in the power grid. To ensure the need for fire linkage and power security, it can provide emergency lighting and fire emergency protection in real time to protect users' lives or the body from injury. The technical requirements are subject to the fire certification supervision of the Ministry of Public Security (GB17945-2000) and accept the acceptance of fire protection at the installation site. However, UPS is only used to protect users' PC equipment or services from economic losses. Its product technical requirements are certified by the Ministry of Information Industry. Both apply different safety standards and therefore have different values.
(2) UPS chooses inverter priority to ensure the quality of power supply, so it is committed to improving the quality of the power supply; while EPS is to ensure priority for city power in order to ensure energy conservation and reliability, and to improve the reliability and mandatory operation of the power supply. Of course, there are also great differences in the design specifications of the rectifier/charger and inverter.
(3) Since the UPS is used on-line and the inverter fails, there is a back-up protection for the utility power and an alarm in time, which allows the user to grasp the fault in time and eliminate it in time, without causing greater losses. The EPS is a backup use, and is the last power supply guarantee. Therefore, its reliability design requirements are higher. It cannot be simply understood as a standby UPS. Otherwise, the importance of the EPS is meaningless. The significance of the backup protection must be emphasized. If the EPS fails to provide emergency power through the battery when the utility power fails, the EPS will act like a virtual one, and the consequences will be disastrous. Sometimes it may be impossible to make up for it with money.
(4) UPS power supply objects are computers and network devices. The load nature is rectification and filtering load, power factor is not much difference, so the national standard specifies the UPS load power factor is 0.6 ~ 0.8, that is 1kVA UPS with the rated load (resistance) can only be 600 ~ 800W; and EPS power supply object is Fire safety and power protection, the load is a hybrid load with both inductive, capacitive, and rectified nonlinear loads. The load power factor cannot be set to 0.8, and some loads are put into operation after the commercial power is interrupted. Therefore, EPS is required to be able to withstand large inrush currents, and EPS needs to have higher output anti-overload capability. Therefore, its dynamic and static control characteristics are different, and for this reason its transfer function will not be the same. Therefore, the allocation of technical design indicators of EPS and UPS components is different, and the related indicators must have certain gains and losses. This is very important and is the key to the comprehensive performance of the product.
3Characteristics of the EPS product When the mains electricity is available, it is in a waiting state without noise; when there is no mains electricity, the inverter works, the noise is less than 60dB, and there is no need for smoke exhaust and shockproof treatment, and it has no pollution or hidden danger of fire, etc. Features.
(1) Automatic switching. Main power supply and EPS power supply switching time is 0.1 ~ 0.25s, high-end machine can be realized unattended, online monitoring;
(2) Strong carrying capacity. EPS adapts to mixed loads of equipment such as elevators, pumps, fans, and emergency lighting. Reliable, general host life of up to 20 years;
(3) Adapt to harsh environments. Can be placed in the basement or power distribution room, or even in the building shaft. It can be set up in the immediate vicinity of the emergency load use site to reduce the power supply line and achieve the most effective end switching;
(4) For some power-intensive facilities, such as fire-fighting pumps and fans, the EPS can be directly connected to the motor to make a power-controlled emergency power supply, which can save the motor's soft start and control box and other settings. The most economical power factor, thus reflecting better economics;
(5) Emergency standby time: The standard type is lighting: 90min, power: 120min; there is a delay interface, which can be long or short.
4 Conclusion In summary, EPS can be used as a reliable green emergency power supply. It is particularly suitable for high-rise building fire protection facilities where there is no second-line utility power and inconvenient use of diesel generator sets. Both can be used in the same way as diesel. The power distribution scheme of the generator is also applicable to some projects as end-use emergency backup power in local and important occasions. Therefore, in selecting UPS and EPS, it is necessary to distinguish the nature, occasion, and purpose of use, and make a reasonable choice. Do not think that EPS is better than UPS or UPS is better than EPS. They have their own uses and have their own design concepts.
1 EPS topology design EPS machine reliability (MTBF) is not a simple combination of basic units. In order to meet the reliability of the entire machine, how to configure the reliability of each basic unit is crucial. In order to ensure the reliability of the whole machine (especially from personal safety and fire escape), the MTBF of the EPS consists of the charger MTBF, the MTBF of the inverter, the MTBF of the low-voltage electrical appliances, and the MTBF of the control unit. It can be seen that the MTBF of the complete machine is formed by the superposition of the MTBF of the major components. Therefore, the overall design of the EPS requires a detailed study, analysis, and calculation of the MTBF of each major component to improve the MTBF of the weak components because the MTBF of the weak component is determined. The MTBF of the whole machine, therefore, needs to configure the security life cycle of each major component from the needs of the overall security life cycle of the EPS.
2 Difference between EPS and UPS EPS is developed from the application of UPS. This sentence is not exact. Because the transfer function of the EPS and UPS core component inverter control system is completely different, it is reflected in the EPS load power factor, load capacity, overload multiple, short-circuit protection of the output circuit, the mandatory operation of the inverter and other parameters and Performance is much better than UPS. General UPS can be used as a voltage closed loop system, while EPS is a multi-closed loop system with current inner loop (as shown in Figure 2), which is the key to EPS. In addition, their related protection is completely different.
(1) The development of EPS in China originated from fire alarms and unexpected failures in the power grid. To ensure the need for fire linkage and power security, it can provide emergency lighting and fire emergency protection in real time to protect users' lives or the body from injury. The technical requirements are subject to the fire certification supervision of the Ministry of Public Security (GB17945-2000) and accept the acceptance of fire protection at the installation site. However, UPS is only used to protect users' PC equipment or services from economic losses. Its product technical requirements are certified by the Ministry of Information Industry. Both apply different safety standards and therefore have different values.
(2) UPS chooses inverter priority to ensure the quality of power supply, so it is committed to improving the quality of the power supply; while EPS is to ensure priority for city power in order to ensure energy conservation and reliability, and to improve the reliability and mandatory operation of the power supply. Of course, there are also great differences in the design specifications of the rectifier/charger and inverter.
(3) Since the UPS is used on-line and the inverter fails, there is a back-up protection for the utility power and an alarm in time, which allows the user to grasp the fault in time and eliminate it in time, without causing greater losses. The EPS is a backup use, and is the last power supply guarantee. Therefore, its reliability design requirements are higher. It cannot be simply understood as a standby UPS. Otherwise, the importance of the EPS is meaningless. The significance of the backup protection must be emphasized. If the EPS fails to provide emergency power through the battery when the utility power fails, the EPS will act like a virtual one, and the consequences will be disastrous. Sometimes it may be impossible to make up for it with money.
(4) UPS power supply objects are computers and network devices. The load nature is rectification and filtering load, power factor is not much difference, so the national standard specifies the UPS load power factor is 0.6 ~ 0.8, that is 1kVA UPS with the rated load (resistance) can only be 600 ~ 800W; and EPS power supply object is Fire safety and power protection, the load is a hybrid load with both inductive, capacitive, and rectified nonlinear loads. The load power factor cannot be set to 0.8, and some loads are put into operation after the commercial power is interrupted. Therefore, EPS is required to be able to withstand large inrush currents, and EPS needs to have higher output anti-overload capability. Therefore, its dynamic and static control characteristics are different, and for this reason its transfer function will not be the same. Therefore, the allocation of technical design indicators of EPS and UPS components is different, and the related indicators must have certain gains and losses. This is very important and is the key to the comprehensive performance of the product.
3Characteristics of the EPS product When the mains electricity is available, it is in a waiting state without noise; when there is no mains electricity, the inverter works, the noise is less than 60dB, and there is no need for smoke exhaust and shockproof treatment, and it has no pollution or hidden danger of fire, etc. Features.
(1) Automatic switching. Main power supply and EPS power supply switching time is 0.1 ~ 0.25s, high-end machine can be realized unattended, online monitoring;
(2) Strong carrying capacity. EPS adapts to mixed loads of equipment such as elevators, pumps, fans, and emergency lighting. Reliable, general host life of up to 20 years;
(3) Adapt to harsh environments. Can be placed in the basement or power distribution room, or even in the building shaft. It can be set up in the immediate vicinity of the emergency load use site to reduce the power supply line and achieve the most effective end switching;
(4) For some power-intensive facilities, such as fire-fighting pumps and fans, the EPS can be directly connected to the motor to make a power-controlled emergency power supply, which can save the motor's soft start and control box and other settings. The most economical power factor, thus reflecting better economics;
(5) Emergency standby time: The standard type is lighting: 90min, power: 120min; there is a delay interface, which can be long or short.
4 Conclusion In summary, EPS can be used as a reliable green emergency power supply. It is particularly suitable for high-rise building fire protection facilities where there is no second-line utility power and inconvenient use of diesel generator sets. Both can be used in the same way as diesel. The power distribution scheme of the generator is also applicable to some projects as end-use emergency backup power in local and important occasions. Therefore, in selecting UPS and EPS, it is necessary to distinguish the nature, occasion, and purpose of use, and make a reasonable choice. Do not think that EPS is better than UPS or UPS is better than EPS. They have their own uses and have their own design concepts.
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