When the utility power is normally 380/220VAC, there is DC voltage in the main DC circuit, which is supplied to the DC-AC AC inverter, outputting a stable 220V or 380V AC voltage, while the utility power is rectified to charge the battery. When any time the utility power is undervoltage or suddenly drops out, then the battery pack feeds power to the DC circuit through the isolation diode switch.
There is no switching time from grid power to battery power. When the battery energy is about to run out, the uninterruptible power supply sound and light alarm, and in the battery discharge lower limit point to stop the inverter work, long alarm. The UPS also has an overload protection function that jumps to the bypass state when an overload (150% load) occurs and automatically returns when the load is normal.
When a serious overload occurs (more than 200% of the rated load), the uninterruptible power supply immediately stops the inverter output and jumps to the bypass state, at this time the front input air switch may also be tripped. After eliminating the fault, just close the switch and reboot the machine to start restoring work.
Expanded information:
One of the flywheel uninterruptible power supply
Before the days of batteries, the uninterruptible power supply used to be a battery operated power supply. Before the age of batteries, uninterruptible power supplies used to use flywheels and internal combustion engines to provide power supply to the load, this uninterruptible power supply is called flywheel or rotary uninterruptible power supply. A flywheel UPS consists of a rectifier, a DC motor, a flywheel, a diesel (or gasoline) engine and a generator.
In the case of grid power, the DC power provided by the rectifier drives the motor to drive the flywheel to rotate, and with a generator to supply power to the load. Due to the inertia of the flywheel, the generator speed can be maintained at a balanced level, and at this time the uninterruptible power supply acts as a filter for grid interference. When the power grid is cut off, the flywheel continues to drive the rotor of the generator to rotate, and at the same time starts the diesel engine to drive the generator to generate electricity, replacing the original grid to supply power to the load.
Because the flywheel type uninterruptible power supply using internal combustion engine to provide electricity, will produce a large noise at the same time the volume is also larger, so at present is generally only used in emergency situations and some natural conditions of the occasion, usually the uninterruptible power supply will be used to provide power to the battery.
Two, battery-type uninterruptible power supply
Since the 1960s General Electric research and production of uninterruptible power supply since the uninterruptible power supply has been improved, but its basic principles have not changed significantly.
Modern uninterruptible power supply consists of a battery pack, an inverter and a control circuit, one end of which is connected to the power grid and the other end to the electrical load. Under normal grid voltage conditions, the UPS utilizes grid power to charge itself, and in the event of grid abnormalities, the UPS releases the power stored in the batteries for use by the load.
It is usually divided into on-line and backup (also known as off-line) according to the mode of operation; according to the output waveform can be divided into sinusoidal, approximate sinusoidal (with a stepped square wave to fit the sinusoidal wave) and so on.
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