Feb 25, 2021
About UPS technical terminology explanation
UPS power supply covers a wide range of fields and is closely related to the household appliances in our daily lives. However, when many netizens buy UPS, they also scratch their heads over some technical terms that appear in the manual. In order to make it easier for non-IT professionals to use UPS smoothly, APC has specially prepared the following small entries of some professional terms of UPS for you, I hope it will be helpful to you.
AC: Exchange. Used to describe the alternating voltage or current in the positive and negative half cycles, such as 230VAC. In an AC power distribution system, the frequency in countries with 230V voltage standards is 50HZ, and in countries with 110V standards such as North America, the frequency is 60HZ. The waveform may be a sine wave, it may also be a step wave or a square wave. The term related to the battery is direct current (DC). The advantage of an AC power distribution system over a DC power distribution system is that the voltage obtained on the secondary side of the transformer may be the positive or negative half of the waveform, and DC means voltage It can only be unidirectional; another advantage of AC power distribution system compared with DC power distribution system is that because of the alternating positive and negative half cycle of the waveform, the voltage, current and energy have zero crossing points. This feature is similar to arc extinguishing. The function of the circuit can eliminate the arc effect that may be caused by the contact resistance change or the instantaneous strong current caused by the long-term use of the switch, the fuse, the relay, and the air switch. This is the case for the DC power distribution system. Is fatal.
Battery: A device used by UPS to store energy. The battery used in UPS is usually reusable. Normally, the battery type used by UPS is lead-acid maintenance-free battery. The electrolyte inside the battery exists in the form of liquid and is leak-proof, which can ensure that the battery can be used no matter how it is placed.
Low voltage: A situation where the input voltage is lower than normal. If the low voltage lasts for more than 1 second, it becomes a voltage dip. Low voltage is usually caused by circuit overload or the power supply company in order to avoid excessive user power consumption during peak power consumption. Studies have shown that low voltage usually affects computer work.
BTU: British thermal unit. It is usually used in the heat dissipation and cooling system of buildings. At the same time, the heat generation of computer equipment must be considered when designing building temperature control. 3.6BTU/hour is equivalent to 1 watt.
Bypass: Refers to the AC path of the UPS. Under the premise of overload or other abnormal conditions, in order to protect the load equipment, the UPS will transfer to automatic bypass operation. When the UPS fails and needs to be repaired or some special repairs are required, the user can transfer the UPS to bypass operation. Maintenance bypass means that the UPS can be completely isolated without interrupting the load. A true maintenance bypass should be completely separated from UPS.
Circuit breaker: When the current exceeds the limit, it will be disconnected to protect the system. During the manufacturing process, the circuit breaker needs to be calibrated to correspond to a given overcurrent value. A large current flowing through a hot wire may cause a fire. Therefore, if a large current flows due to equipment failure or user error, the circuit breaker can be tripped to avoid overheating of the wire. For building wiring and power distribution systems, the capacity of the switchboard air switch must comply with national standards.
Common mode interference: For an AC system, common mode interference refers to noise or surges on the power supply line. Common mode interference exists between the live wire and the ground wire, and between the neutral wire and the ground wire. In most countries, the neutral wire and the ground wire are usually connected to the maintenance switchboard, that is, the circuit breaker is connected to the ground wire, so there is no common mode interference. However, unexpected noise signals in the neutral wire or the ground wire, wiring errors, Factors such as overload current will cause the existence of common mode interference. Today's computer loads can isolate common mode interference. Common mode interference is usually mixed with ground noise between systems, causing computer damage or data loss.
Crest factor (Crest factor): Crest factor, or crest factor, refers to the ratio of the peak value of the current to the average value. The crest factor of the square wave is 1. The crest factor of the sine wave is 1.414.
The crest factor of an ordinary computer power supply (such as mains) is 4. In this case, the crest factor is 4 mainly because of the complex interaction between the input and the load. When the power supply of the computer load is UPS, the crest factor is reduced. The reduction of the crest factor when the UPS supplies power to the load will not have a bad effect on the computer equipment, on the contrary it is beneficial to its work. The crest factor is the product of the interaction between the power supply and the load, so it has no meaning for the load and the power supply. The factors that affect the high crest factor provided by UPS are usually: the output impedance of each harmonic; the distortion of the output voltage waveform and the maximum current. Although high crest factor is a measure of UPS output stability and output voltage quality, different measurement techniques make product performance based on the crest factor as a standard more meaningless. At present, the commonly used method is to assess the value of the output voltage or the distortion of the output voltage waveform when carrying a step-type load.