First, the controller detects a power failure and to double the power to issue movement commands, the first indication breaking common dual power supply.

Second, breaking the common power supply, the controller instructs the switch conversion action. At this point, if it is two-stage dual power switch, the direct conversion to standby power supply side, if it is three-stage dual power, can stay in the middle of zero work place, breaking the common power supply and standby power supply by a control bit,, decides whether to switch to backup power side. The user can decide whether to have a dwell time "stay" position and specific settings according to the characteristics of the system and the controller.

Third, this time the line has been connected to the standby power supply side. In order to protect the critical load of the power supply, we still need to consider the following three aspects, corresponding, dual power switch is also required to have the following three features.
1, the power failure did not occur, dual power switch is not disconnect the normal power supply.
Early contacts dual power supply (voltage fluctuations can cause changes in the contact pressure is automatically breaking moment undervoltage) and dual power supply circuit breaker (overload, short-circuit automatic breaking) the possibility of supply problems due to the non-existence of breaking the circuit, and do not meet this requirement. To isolate the switch as the switch body and the special type of PC-class dual power switch, with mechanical hold function, only under instructions issued by breaking the power supply and conversion, for this requirement in the controller.
2, the ability to withstand the impact of current
Burned as a result of over-current dual power reasons, will result in significant losses, so need to have the ability to tolerate dual power surge current. Corresponding dual power GB and IEC standard specifies the minimum ATSE short-time withstand current of 5000A (or 20Ie), is a low-voltage electrical switches in the most demanding, but also objectively reflect the demands. In order to achieve a high withstand current capacity, the need to re-design, selection of contact material to withstand greater contact pressure, which is the world"s leading professional suppliers of dual power switch is not used directly as a ready-made body of the other low-voltage switchgear components, but rather spend a lot of manpower and resources to completely re-design and development of the root causes.ASCO, GE"s dual power switch of this indicator is very high, both companies claimed that the index is a key indicator dual power switch. Gradually increase the ability to withstand the impact of the development direction of the current dual power switch.
3, the fault condition and reliable conversion capability.
In the case of normal power supply fails, and the standby power supply is working properly, the dual power switch must reliably protect the load switch to backup power, dual power switching mechanism, the switch is turned on and breaking capacity, and reliability of the controller is the requirement the effective protection. Specific requirements are as follows:
The controller can accurately detect a variety of power failure.Strictly speaking, there are nine kinds of power failure ATSE type, standard in any one phase or multiphase phase failure, undervoltage dual power switch must be converted in fact only a minimum requirement, the ideal dual power switch controller should be able to effectively detect 9 kind of a power failure, and then need to decide must be converted or may not be converted. Controller technology performance and reliability, are often not pay attention to industrial users (and this is the biggest difference with other low-voltage power switch double switch), but also reflects the use of the product in terms of immaturity, in fact, switch electrical, mechanical properties reached the international advanced level is not difficult, but to reach the international advanced level in terms of performance and reliability of the controller, there is a long way to go.