got my exam coming up next week and been doing a few mock exams.
just wondered if anyone could help my with the following 2 which I have got wrong a couple of times and need to see where im going wrong
Q1.
Cable selection for a motor circuit. A 3 kW/230v 50Hz singles phase motor has an efficiency of 70% works at a power factor of 0.6 lagging.It is fed by single core copper conductors run through steel conduit (method 3). The cable is 25m long and the voltage drop must not exceed 6V. If the ambient temperature is 25oC and the circuit protective devices are BS 88 fuses, determine a suitable size cable for the installation. Assume the disconnection time and thermal constraints are both satisfied.
For this I got 1.5mm2
Q2.
Cable selection for an industrial load A heater rated at 16Kw is fed at 400V 50Hz. A three phase 4 wire supply is to be installed in a factory using PVC non armoured copper conductors multicore cable, The cable is 25m long and is installed clipped direct to a wall. If the ambient temperature is 35oC and the circuit protective devices are BS 3036 fuses, determine a suitable size cable for the installation. If the 3036 fuses were replaced by BS88(Cg) fuses what would be the effect on the cable current rating.
I put 6mm2 for this and that the fusing has no change
thanks
mrjammin
just wondered if anyone could help my with the following 2 which I have got wrong a couple of times and need to see where im going wrong
Q1.
Cable selection for a motor circuit. A 3 kW/230v 50Hz singles phase motor has an efficiency of 70% works at a power factor of 0.6 lagging.It is fed by single core copper conductors run through steel conduit (method 3). The cable is 25m long and the voltage drop must not exceed 6V. If the ambient temperature is 25oC and the circuit protective devices are BS 88 fuses, determine a suitable size cable for the installation. Assume the disconnection time and thermal constraints are both satisfied.
For this I got 1.5mm2
Q2.
Cable selection for an industrial load A heater rated at 16Kw is fed at 400V 50Hz. A three phase 4 wire supply is to be installed in a factory using PVC non armoured copper conductors multicore cable, The cable is 25m long and is installed clipped direct to a wall. If the ambient temperature is 35oC and the circuit protective devices are BS 3036 fuses, determine a suitable size cable for the installation. If the 3036 fuses were replaced by BS88(Cg) fuses what would be the effect on the cable current rating.
I put 6mm2 for this and that the fusing has no change
thanks
mrjammin
