Online double conversion ups output isolation transformer based three phase

Bypass Circuit

With the “static switch” intelligently controlling the electronic switching circuit, the loads can be powered by both the inverter and the bypass circuit. Under normal conditions, the loads are powered by the inverter whose static switch is closed. In case of overload (beyond the overload time limit) or fault with the inverter, the static switch will automatically switch to the bypass circuit.
Under normal conditions, complete synchronization of the inverter output and bypass power is a must for achieving uninterrupted switch between inverter output and bypass power. Given such requirement, when the bypass power frequency is within the locking range, the inverter output frequency in the inverter-controlled circuit is tracking the bypass power frequency. What’s more, there is also a manual maintenance bypass switch in the UPS system. When the UPS needs to be shut down for maintenance, the bypass power will directly supply power the important loads via the manual maintenance switch.

Note: When the loads are powered by bypass or maintenance bypass circuit, the power supply is not guaranteed.

Proper Functioning

When the UPS is functioning properly (i.e. when the UPS input AC is normal, the rectifier and the inverter are functioning properly), the loads are powered by the inverter, the battery switch is closed, and the battery is under the steady floating charge by the DC busbar voltage. (“1+N” parallel UPS system) Note: As the output of all the UPS stand-alone machines are connected in parallel, the system will check whether all the inverter-controlled circuits are operating synchronously, and whether the frequency and phase are in consistence with those of the bypass circuit. The output of each circuit should stay the same. The current for the loads is evenly supplied by each UPS stand-alone machine. In the course of synchronization, the UPS system will display corresponding warning message.
Only when the above requirements are met will the static switch of the stand-alone machine is closed.

Abnormal AC

In case of AC power failure or abnormality, the rectifier will automatically stop working, and the system will switch to battery inverter output, the inverting time of which depends on the loads and the battery capacity. If the AC is still not back to normal during this period of time, the inverter will automatically stop working, and the UPS operating control panel will display corresponding warning message. The interruption and recovery of the AC do not disrupt power supply to the loads.

AC Recovery

If the AC recovers within certain time, the rectifier will automatically start (and its output power gradually increases), supply power to the loads and charge the battery, hence no interruption in the power supply.

Maintenance Bypass Circuit

There is another bypass circuit for the UPS system, i.e. the maintenance bypass circuit, which is used to provide a safe working environment for the technical staff when they are carrying out regular maintenance or repair for the UPS system, and also to provide AC power for untreated loads. The maintenance bypass circuit can be manually selected via the bypass circuit switch, and cut off when switched to “OFF”.

Output Isolation Transformer Based UPS are available from the range of 10KVA to 800KVA with an option to connect parallel units up to 8nos. Output Isolation Transformer Based UPS are widely used in Cathlab UPS, Industrial UPS, Semi Industrial UPS, UPS for the Manufacturing Facilities.