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DC Voltage Sampling Box PFU-2

editor:admin    date:2014-07-22


AC automatic switchover box mainly functions to realize automatic switching between the two AC inputs. It has the following features.
Automatic switching between master and standby AC inputs.
AC Input I is the main input and Input II is the standby input. In case of abnormality of AC Input I (such as no voltage, overvoltage, undervoltage or phase failure), the system will switch to AC Input II provided that AC Input II is in a normal condition. If AC power of Input II is abnormal itself, it’s impossible to complete automatic switching. Once AC Input I is recovered, the system will switch back to AC Input I automatically. There is a 3~5s delay in the powering-on and switchover process of the system.
Automatic switching and protection against AC input overvoltage and undervoltage
According to sampling voltage, the box will realize AC automatic switching and protection against overvoltage and undervoltage. After the AC voltage is sampled, the system will compare it with the preset reference AC overvoltage and undervoltage value, and produce logical control signal accordingly to control AC contactor to perform switching and protective actions.
AC contactor working mode: close at high voltage and maintained at low voltage
As AC contactor needs powering on for long time to keep its contacts close, it’s inevitable for its coils to produce some heat, and accumulated heat for long time will reduce its life. The AC contactor adopts the design of close at high voltage to ensure reliable close of the contactor. When the AC contactor is securely closed, the AC control box outputs rated low voltage DC signal to maintain the close state of the AC contactor, thus effectively ensuring longer life span and higher reliability of the contactor.
Mechanical and electrical interlink
To prevent two AC inputs from being connected to the rectifier input terminal simultaneously, provision of an interlocking mechanism is necessary. AC automatic switchover box allows for electrical interlock control. With appropriate AC contactor, you can realize mechanical interlock.
See the following table for specifications of the AC automatic switchover box.
Power source
Two single phase inputs
Range of input voltage
Type of AC sampling signal input
3-phase AC
Amplitude 220v vs 6.5v
Drive capability of contactor
Each circuit less than 500mA
High voltage closing voltage
Surge current on the recommended contactor is about 2A
Maintain close state at low voltage
Switching time
3 seconds
To be re-started, 8 seconds after being powered on again
Switching point of undervoltage
Switch to the other AC input when the voltage is lower than this point
Switching point of overvoltage
Switch to the other AC input when the voltage exceeds this point
Undervoltage protection point
Protection when both AC inputs lower than this voltage