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Thyristor switch


1. Important information

This documentation points to specialists enabling them to select and connect the static contactor TS as well.

Any application of TS must comply with national tules any time ,even though not specified in this documentation.

2. Application

Static contactors TS are used for switching capacitors in 3-phase-systems. In comparison with contactors the static contactor calls special attention to switch in without inrush current, smooth disconnecting procedure and high switching frequency. These characteristics will be guarantees by firing unit, basic characteristic of thyristors and diodes and HL recommendations.
Static contactors TS are used when rapid, high frequently, switching of capacitors is requested without any disadvantageous reactions.

  These demands could appear following items, especially:

■Windmill plants
■Lifts and Cranes
■Primary pulsed welding plants

3. Components of contactors
Static contactor TS basically contents components as following:
Thyristors,diodes,heatsink,firing unit
Thyritors are semi-conducting units,which may be controlled by firing impulse at gate from locked into semi-conducting condition,semi-conduction means current may flow in "one way" direction,from anode to cathode.Thyritors will lock again,if flowing current decreases to zero .to control alternating current,thyristor and diode in an antiparallel mode are requested,as provided in TS. As with all active components on-state voltage and forward slope resistance define power losses between anode and cathode at semi-conductors,finally which result in heat tu be diverted by heatsink.
The firing unit becomes significant; it generates firing impulses to control thyristors into semi-conducting condition,firing impulses will be started by an external DC-voltage 12v,to avoid any inrush current the impulses will be transmitted to the gate of the thyristor in case of  voltage between anode and cathode becomes switching capacitors this means during switching procedure.
Due to the continuos load of disconnected capacitors to peak of mainsvoltage ,the discharging devices must be dimensioned correctly .in pratical use ,this means that discharging reators are not allowed to be used ,because the continuos DC-voltage would destroy them .it is recommended to use discharge resistors ,which are dimensioned for a permanent connection to DC-voltage in height of peak voltage of the mainsvoltage. 

4. Switching mode

Static controller TS may be used in choked capacitor banks and un-choked as well. Please take care that in unchecked capacitor banks may be thyristors are destroyed by current transients, which are cause by fast changing of the voltage, at choked capacitors banks please take care that the higher current are not exceeding the max, current of static contactor.


                         connection diagram

5. Installation of the static contactor TS
Thyristor swiches of type TS have to be placed in this way, that no danger for people is caused, typically this is achieved by mounting them in a switchboard.
When installing the switches it is to be respected, that in the thytistor losses are generated ,which have to be hand out to environment by the heat sink .in continuos operation temperature up to 100℃ are possible at heatsink .because of this the static contator has to be mounted in the way ,that no other componts or cables are damaged because of the high temperature .Distances have to be chosen accordingly. Additionally it is prohibited, that connection leads have contact with extreme high currents can be caused.


6. Electrical connection of static contactors

thyristor switches can’t separate electrical circuits .because of this suitable arrangements for the separation from the power system have to be made .the lines have to be protected regarding the electrical regulations in general capacitor switching thyristors are to very hard environmental conditions .caused by the charge of the capacitors the voltage at the thyrisors can reach the double peak mains voltage .especially for the useage with non-choked capacitors very high current can occur caused by voltage transients .furthermore short circuit in the grid are supplied by the discharging currents of the capacitors .these current can damage the thyristors!

7. Maintenance of static contactors

Grenerally thyristor swiches are maintenances-free. But nevertheless some points have to be repected :

a) Thyristor  switches, equipped with fan,have to be checked for the correct fan function every 2 years, if a fan is defective ,it has to be replaced by the original part. Using another fan with less air flow can cause over overheating and this can destroy the thyristors.

b) Genera;;y the heat sink have to be cleaned regulary, because the cooling capacity can be reduced by pollution.

c) Pollution between the connections of the thyritors have also to be removed, because of this leakage distances are reduced. This can cause a voltage flashover.

8.Technical Data


9. Mechanical drawings


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