As shown within the dotted lines in Figure 1, a high-capacity fast switching device consist of a bridge FS, a fuse FU, a nonlinear resistor FR, and a testing and control unit CT. The device is abbreviated HDF and its symbol is .
Under normal circumstances, the bridge has the eectric current flow through it. In case of a short circuit, the bridge disconnects quickly within 0.15 ms.
The short circuit current is diverted to The fuse upon the bridge’s disconnection.
It fuses within 0.5 ms and produces an adequate arc pressure.
The arc pressure produced by fusing absorbs the magnetic field and limits the overvoltage occurring at the disconnection within an allowable level.
This unit monitors the electric current and its rate of change. It sends a disconnecting signal to the bridge in case of malfunction.
Features of high-capacity fast switching device
Due to its new principle, advanced technology and fine design, the high-capacity fast switching device is superior to a conventional protector with a breaker plus a relay.
20 times faster
The failure current is broken within 1 ms and drops to 0 within 3 ms, and the failure is completely eliminated.
The conventional protector with a breaker Plus a relay would take at least 60 ms to break a failure current.
Higher sensitivity with current’s rate of change closely monitored When a failure current occurs, an increased rate of change is shown.
When a current has its amplitude and rate of change exceed the normal values at the same time, it is judged a short circuit.
The three identical independent testing and control elements will judge a failure based on their “votes”, and set off a disconnecting signal without error.
Unlimited breaking capacity
Normal working current flows through the bridge.
The arc pressure produced by the high breaking capacity fuse will close the nonlinear resistor, which will distinguish the arc of the fuse.
Once equipped with a nonlinear resistor to absorbs the magnetic field, the breaking capacity may be substantially enlarged.
The system will never experience an anticipated impact current.
The failure current is broken within1 ms and drops to 0 subsequently.The breaking current value l p will be onlyabout one tenth of the peak short circuit
value l max.
The system will experience a much smaller electric force,with the passed l2t being only one several thousandth of that in a breaker-type protector.
No damaging overvoltage in the process of disconnection
The zinc oxide nonlinear resistor will limit the over voltage within the 2.5-time rated phase voltage specified by the national standard.
Advantages of high-capacity fast switching devices used in electric systems
The mechanical strength design of the electric equipment may be slackened as the equipment with this device will not be impacted by any strong short circuit current.
The size of the conductor may be reduced due to the electric equipment’s fast disconnection and lower breaking current that eliminate the problem of thermal instability.
Protection for large electric generators against outlet short circuit
With a large breaking capacity,it is an ideal breaking device for electric generator outlets and
Electric generators and transformers areprotected fast and effectively.
Much lower investment requirement for system expansions and network operations
At a short circuit, HDF quickly Disconnects a system with the load-side breaker handling a short
circuit current of a single transformer. It will not be necessary to replace the Original switching equipment for system expansions. Electric systems’ reliability will be raised With reduced voltage drops at heavy load starting.Operations will be more economical.
Parallel connection of HDF and reactor as the most economical and efficient limiting scheme
Normally, HDF short connects the reactor to avoid huge power consumption by the reactor and the voltage drop at the starting of a large motor.At a short circuit, HDFdisconnects quicklyand the load-side breaker’s breaking current is limited by the reactor within allowable levels.
In the design of a new power supply system, the impedance of the reactor may be raised to help
further reduce the load-side breaker’s breaking current,thereby reducing the cost.
Higher quality of power supply for important loads that do not allow any instant outage or that require forced auto-starting
At a short circuit, HDF disconnects quickly and activates the reactor.The residual voltage on the reactor may be designed to a level that is sufficientTo maintain the operation of an important load.
Model specifications and technical parameters
Construction of high-capacity fast switching device
Ambient temperature: -40℃ ~ 50℃
Altitude: not more than 1,000 meters; special design neededforaltitude of over 1,000 m.
Environmental conditions: free from dust, corrosive gas, steam, or explosive gas
Relative humidity: 90%
Packaging, transportation and storage
To be packed in wooden case, with the cabinet base fastened to the bottom panel of the package.
Not to be transported over long distance on highways below grade three.
May be repacked for shipping as necessary.
To be stored in a dry warehouse with good ventilation if not used for a long time. Not to be stored outdoors for long. Main components of HDF shall be free from collision, dampness or exposure to the sun when in transportation.
Selection of parameters and technical service
Our HDF design shall accommodate parameters of customer’s generator, transformer and line arrangements.
Cabinet design shall be made according to the size of the customer’s installation site.
Assistance and technical guidance may be provided on request for on-site installation and testing.
The bridge’s disconnecting signal must not be open circuited. It should be safely shorted for installation and testing.
Instructions for ordering
Customers shall provide parameters/drawings of their generator, transformer and site line arrangements.
Customers shall indicate types, specifications and quantity of spare parts they need.
We are specialized in reactive compensation related products manufacturers, reactors, capacitors, transformers, cables and wires and other products. Our company, founded in 1998, has been one of the earliest manufacturers of reactive power compensation in China for more than 20 years.