(a) 748 800 J on although the current 28 800 J drops below 3A when it is Standby = 138 240 J in normal operation. More Full Power = 140 400 J current is required to start Full for 45 minutes the motor. uses up more energy. 3 A fuse (I = 0.87 A) (a) 306 000 J 2.5 hours 10 A fuse ( I = 5.2 A) 158 400 25 200 – = 133 200 J 13 A fuse (I = 10.9 A) 1300 W 5A fuse (I = 4.35 A) Power, Current & Voltage Fuses (p53) (p51 52) Power & Resistance (p54 57) – – The fuse protects the (a) 1.35 W flex of an appliance from P = I V 18 W damage due to a high P = I x IR 30 A current. P = I2 R 5 A 50 V If a fault occurs, the (a) 225 W 40 V current can get much 32 W higher than is safe (up to 2 A 759 W 13 A). This can cause 0.2 A dangerous overheating of 15 Ω 3.5 A the flex. 10 000 Ω 12 V The fuse will blow as 7.2 W the current is greater than 0.52 A 3 A. 4 A 110 V (approximately) The current is 3A 48 Ω when the vacuum is turned
(a) 748 800 J 28 800 J Standby = 138 240 J Full Power = 140 400 J Full for 45 minutes uses up more energy. (a) 306 000 J 2.5 hours 158 400 – 25 200 = 133 200 J 1300 W Power, Current & Voltage (p51 – 52) (a) 1.35 W 18 W 30 A 5 A 50 V 40 V 759 W 3.5 A 12 V 0.52 A 110 V (approximately) Fuses (p53) The fuse protects the flex of an appliance from damage due to a high current. If a fault occurs, the current can get much higher than is safe (up to 13 A). This can cause dangerous overheating of the flex. The fuse will blow as the current is greater than 3 A. The current is 3A when the vacuum is turned on although the current drops below 3A when it is in normal operation. More current is required to start the motor. 3 A fuse (I = 0.87 A) 10 A fuse ( I = 5.2 A) 13 A fuse (I = 10.9 A) 5A fuse (I = 4.35 A) Power & Resistance (p54 – 57) P = I V P = I x IR P = I2 R (a) 225 W 32 W 2 A 0.2 A 15 Ω 10 000 Ω 7.2 W 4 A 48 Ω