Electrical and plumbing (T5)

Question 1

Faraday’s Law of Induction

Answer 1

a changing magnetic field will interact with an electrical circuit to create an electromotive force

Question 2

electromotive force

Answer 2

the characteristic of any energy source capable of driving electric charge around a circuit

Question 3

current

Answer 3

the flow of electric charge (C/s = A, Ampere)

Question 4

voltage

Answer 4

an electromotive force or potential (Volts, V)

Question 5

power

Answer 5

current x voltage

Question 6

how is electricity generated

Answer 6

Say you have a square piece of wire in an magnetic field
Currently no current will be induced because there is no CHANGE in magnetic field. The field is constant
What if we begin to rotate the wire in the magnetic field?
The portion of the magnetic field perpendicular to the surface decreases.
To the coil, the magnetic flux is reducing meaning a current will be induced in the wire

Question 7

what systems are involved

Answer 7

Electrical System: Electric Generator & its Design

Mechanical System: Power Plant to Generate rotational motion

Question 8

three phase electricity

Answer 8

Electric Generator with three wire loops
Provides the benefit of producing a constant instantaneous power
The arrangement allows the transmission of power with less wire

Question 9

how does electricity get into our homes (simple way)

Answer 9

generation
transmission
distribution

Question 10

how does electricity get into our homes

Answer 10

• Electricity is transmitted through wires and long wires act as resistors.
• Resistors “resist” the flow of electricity typically transforming some of
the energy into heat

Question 11

how to diminish the power lost during transmission

Answer 11

electricity is transmitted at high voltages, and then reduced as it gets closer to the load

Question 12

transformer

Answer 12

an electrical device used to increase or decrease the alternating voltages in electric power applications

Question 13

windings

Answer 13

In the primary winding, the alternating current induces a magnetic flux in the transformer core. The magnetic flux then induces a current in the secondary winding.
The change in the voltage is proportional to the ratio of the number of windings.

Question 14

commercial building

Answer 14

• Lighting
• Plug Loads
• HVAC: Chillers, Large
Pumps, Fans
• Lifts and Escalators
mechnaincal services 445

Question 15

Load diversity

Answer 15

• Multiplicity of similar items which are unlikely to be used concurrently
• Spaces on a site that are used at different times
• Usage patterns, operation or process, that include control features to minimize consumption

Question 16

how is electricity billed

Answer 16

Homes and Small Businesses
• Fixed Charge, pence/day
• Unit Charge, pence/KWh

Large Businesses, Campuses,
Industrial Sites
• Fixed charge, pence/day
• Capacity charge pence/kVA/day
• Unit Charge, pence/kWh
• Excess reactive power charge, pence/kVAr

Question 17

foul water drainage

Answer 17

• The waste from sanitary conveniences and other sanitary appliances, equipment used for catering or washing purposes

Question 18

Foul Water Drainage Regulations

Answer 18

• A complete drainage system
• conveys the flow of foul water to a foul water outfall (a foul or combined sewer, a cesspool, septic tank or holding tank);
• minimises the risk of blockage or leakage;
• prevents foul air from the drainage system from entering the
building under working conditions;
• is ventilated;
• is accessible for clearing blockages;
• does not increase the vulnerability of the building to flooding.

Question 19

Primary Ventilated Stack

Answer 19

• Open Gravity Based System where pipes are empty except when the flow is taking place
• To enable this there is a constant fall towards the discharge points
• The entry points are closed by water seals
• The choice of pipe gradient, diameter and connection point is governed by the nature of the fluid flow in the system

Poor system design can lead to pressure fluctuations that can result in:
• Noisy systems
• Loss of water seal
• Bridge traps with fluid from
the system