Working principle:

Under the normal working condition, the bimetal strip in the main circuit of FTB1(the overcurrent protection circuit breaker with selectivity) works the same way as the regular MCB, acting as the overload protection device. When a short fault occurs in one certain branch, the iron core wrapping around by the magnetic coil in main circuit immediatelyworks on the moving contact to produce arc so that the short-circuit current is effectlivy limited in no time. Meanwhile, the short-circuit current in the main circuit flows to the supplementary one. With a current-limiting resistance and a selective bimetal strip in series in the supplementary circuit , the short-circuit current is quickly limited to around some hundred AMP. In the case of short-circuit current be cut off by MCB of faulty branch in load-side, the moving contact in main circuit recloses under the spring's function to make sure that the other good branches work functionly. If the short circuit occurs between the main circuit breaker and MCB or after, with MCB and other short-circuit protection devices unable to cut off the faulty branch, the selective bimetal strip will be able to release the tripping mechanism within 10ms~300ms, to open the contact and maitain its opening position as well as to disconnect the faulty branch.

Features:

Product name	FB1-SMCB
Type	FB1-100(Thermal type), FTB1L-100(Thermal type with residual current protection), FB1Z-100(Electornic type)
Rated voltage	AC230/400V
Rated current(A)	20, 25, 32, 40, 50, 63, 80, 100
Poles	1P, 2P, 3P, 4P
Tripping characteristics	Characteritic E (Overload long time delay, short-circuit short time delay )
Modularization dimension	With width the mutiple of 9mm, single pole can be combined to mutiple poles
Arc distance	< =35mm
Accessories	Per customer's requirements, below accessories can be furnished, like under voltage release, shunt release, auxiliary contact, alarm, power-driven mechanism, generatrix adaptor, etc.