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The conventional relay type of electromagnet relays can be replaced by static relays which essentially consist of electronic circuitry to develop all those characteristics which are achieved by moving parts in an electro-magnetic relay. For example, in an induction type relay, the operating time can be adjusted by adjusting the distance travelled by the disc whereas in a static relay it can be achieved by adjusting the value of the resistance in the R-C time delay circuit. In other words static relays are capable of performing the same functions with the use of electronic circuit control as an electro-magnetic relay performs with the use of moving parts or elements.〔(Induction Type Relays ). CircuitManiac.com. Accessed March 8th, 2012.〕 Static relays are superior to electro-magnetic relays in the following aspects: #The moving parts and the contacts are largely eliminated. The only moving element in a static relay is the final tripping contact. #C.T.s and P.T.s employed are of lesser VA rating as static relays require a very little volt-ampere for their operation. #More precise and high speed operation.〔(Fundamental Relay-Operating Principles and Characteristics ). G.E. Digital Energy. Accessed March 8th, 2012.〕 ==Structure== Static relay consists of following units for operation: #''Auxiliary Voltage Supply:''24 V DC supply is required for energizing the circuitry of the static relay. This is obtained by converting 230 V AC to 24 V DC and in some cases station battery voltage of 110 V to 24 V DC. #''Comparator:''It compares the actual quantity with the pre-set quantity. For example in an over-current relay it will compare the actual current supplied by CT with the pre-determined set current over which tripping is required. #''Time delay Elements:''The required operation time is achieved here by adjusting the values of R and C. #''Logic Circuit:''By using the gate circuits conditions of operation of relays are set and relay can only be operated when these conditions are satisfied. #''Output Device:''The actual tripping of relay can be achieved by firing the SCR or operating the attracted armature type relay by feeding the signal coming from logic circuit output. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Static relay」の詳細全文を読む スポンサード リンク
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