Miniature Circuit Breaker FTB1
Use for places that require higher electric safety and reliability. Insolating the electric equipment and meet the requirement of front and back overcurrent protection device selectivity.
Exterior and dimensions
|Auxiliary contact||Auxiliary contact and alarm contact||Shunt release||Shunt release and auxiliary contact||Under voltage release||Over voltage release||Busbar mounting base||Motor-driven operation|
Under normal condition, the working principle of main thermostic bimetal in FTB1 SMCB is the same to the usual circuit breakers, it is used for overload tripping. when there is a short-circuit on a branch circuit breaker, the magnet core in the main current path would tilt the moving contact away from the fixed contact to break the circuit,thus producing the electric arc, and limiting the short-circuit current effectively.
In the maintime,the short-circuit current flow to the supplementary current path, a selective resistor and a selective bimetal are connected in series of the supplementary curret path, limiting the short-circuit current to a few hundred amps.
When the downstream circuit-breaker has tripped because of a short-circuit, the contact tips reclose automatically through a simple spring-type system,ensuring other unaffected branch circuits continue in operation.If a short-circuit occur between the FTB1 and the downstream circuit-breaker, another bimetal release enables short-time delayed tripping,ensuring the contact tips remain in the open position enabling isolating.
Scope of use
It is primarily used in critical installations,for instance, office buiding, laboratory, theatre, museum, hotel, shopping mall, telecommunication, coal mine and shipping, chemical industry and metallurgy, industrial plants,medical and health care, bank and securities exchange,airport, underground express way, military establishment and similar loads that requires non-interrupted and reliable power supply.
|Test||Tripping characteristic||Conventional non-tripping current||Conventional tripping current||Initial status||Tripping time|
|a b||E E||1.05In||1.2In||Cold statusRight after test 1||≧2h﹤2h|
|Test||Tripping characteristic||Delayed tripping current||short-time delayed tripping current||Initial status||Tripping time|
|c||E||5In||Cold status||0.05s<t<5s(In≦32A) 0.05s<t<10s(In>32A)|
The FTB1 series operates selectively with respect to the combination with MCBs
|MCB(B,C characteristic) FTB1(Characteristic E)|
Note: T represents total selectivity
Exterior and dimensions