Heat generated by heating the heating wire R 1 when the circuit works normally for 6 minutes and 40 seconds:
q plus = W plus = P plus T = 1500 W×(6×60s+40s)= 6× 105j；
(2) The temperature control switch S 1 is turned off, and when the temperature control switch S 2 is turned on, the motor is connected in parallel with the insulated heating wire R 2 and works normally at the same time.
Electric energy consumed by insulated heating wire:
P guarantee =P total -P dynamic =1200 w-1100 w =100 w,
∫ The voltages at both ends of each branch in the parallel circuit are equal,
∴ according to P= U 2 R, the resistance value of insulated heating wire R 2 is:
R2 = U 2p =(220V)2 100 W = 484ω。
Answer: (1) When only the switch S 1 is closed, the circuit works normally for 6 minutes and 40 seconds, and the heat generated by heating the heating wire R 1 is 6×105j;
(2) The resistance of insulated heating wire R 2 is 484 Ω.