Circuit diagram of ceiling fan; Fault finding in ceiling fan

Ceiling fan is integral part of every house and Industry. In this article we discuss about wiring of ceiling fans and circuit diagram of ceiling fans.

Ceiling fan are having “Capacitor Start capacitor Run motor”. These motors have capacitor in series with starting winding. Capacitor used for this is electrolytic type. Due to this capacitor single phase get divided into two phases, due to this magnetic field is produced and due to which motor starts to rotate.

Circuit diagram for ceiling fan is as shown below where capacitor is connected in series with starting winding.

How to reverse the direction of ceiling fan?

Direction of Ceiling fan motor can be reversed connecting capacitor with running winding instead of starting winding. 

Wiring of ceiling fan:-

Ceiling fan connected to power supply through a switch and regulator.  Usually phase is rotated through switch and regulator and neutral is directly connected at ceiling fan. Fan regulator is used to control the speed of fan.

Faults in Ceiling Fan:-

There are two types of faults:-

(A)               Mechanical faults

(B)               Electrical Faults

A)     Mechanical faults:-

There are following Mechanical faults occur in fans:-

(i)                  Bent in shaft

(ii)                Bearing problem

Due to all above faults fan may not run properly or run very slowly.

B) Electrical Faults:-

(i) Main running winding get Open circuit/Short circuit.

(ii) Main starting winding get Open circuit/Short circuit.

(iii)               Capacitor get Open circuit/Short circuit.

(iv)              Earth Fault.

(v)                Fan motor rotate in reverse direction.

For (i) & (ii) faults types detection will be done through this method:-

Open/ Short circuit in winding can be detected by using Test bulb arrangement. Arrangement for the same is as shown below:-

If  bulb doesn’t glows then there  will  disconnection in the winding.

If bulb glows full then there will be short circuit in the winding.

If bulb glows very dim then there is no fault in the Winding.

For (iii) fault capacitor can be checked by using multimeter for it’s value if value is found low then capacitor will be changed. Usually capacitors used in Ceiling fans have 2.5 microfarad rating.

For (iv) fault earth fault can be checked by using multi-meter.

For (v) fault i.e. for reverse direction same can be changed by changing capacitor bank connection to other winding.

In Single Phase motors why There are more turns on running winding in comparison to start winding?:-
In Running winding no. of turns are kept higher than starting winding the reason behind this is to create phase difference in current in both windings to obtain required torque for rotation of motor.
In Start winding when we keep lower no. of turns than there will be less inductance and more resistance so current will be in phase with voltage. Now by keeping higher no. of turns in running winding we will obtain more inductance and lower resistance which will leads to current lagging behind voltage so we will obtain required phase difference.

Faraday's law of electromagnetic Induction

Faraday’s law of electromagnetic induction explains about working principle of following:-

(i)                   Induction Motors

(ii)                  Generators

(iii)                 Transformers

(iv)                 Inductors

This law was given by Michael Farday.

This law provides relationship between current and magnetic field.

There are two Faraday laws of Electromagnetic Induction as stated below:-

Faraday's First Law of electromagnetic Induction

According to this law whenever there is change in the magnetic field of a coil there will an emf to be induced in the coil. This induced emf is called as induced emf.

If circuit of conductor is closed then induced current will also circulate through the circuit.

There are following Methods to change magnetic field

(i)                   Magnetic field can be changed by Moving magnet away or towards the coil

(ii)                  Magnetic field can be changed by moving coil into or out of magnetic field.

(iii)                 Magnetic field can be changed by changing area of magnetic field in which coil is placed.

(iv)                Magnetic field can be changed by rotating coil relative to magnet.

Faraday's Second Law of electromagnetic Induction

According to this law the magnitude of emf induced in the coil is equal to the rate of change of flux that linkages with the coil.

Flux linkage of the coil is the product of number of turns in the coil and flux associated with the coil.

How Faraday law of electromagnetic Induction works:-

Let’s take a Galvanometer connected through a coil as shown below:-

 Now when a Magnet is taken close to this coil, galvanometer needle get deflected from its center position in one direction. Now if galvanometer is taken back to it’s original position then needle will get deflected towards it’s original position.

Similarly if we take galvanometer in opposite direction then Galvanometer needle will move in opposite direction indicating a change in polarity. Then by moving the magnet back and forth towards the coil the needle of the galvanometer will deflect left or right, positive or negative, relative to the directional motion of the magnet.

Now let’s consider magnet approaching towards a coil. Now consider instants Ta and Tb:-

Now Flux linkage with the coil at time, T_a = NΦ_a Wb

Flux linkage with the coil at time, T_b = NΦ_b wb

So Change in flux linkages will be = N(Φ_b – Φ_a)

Now change in flux linkage will be, Φ = Φ_b – Φ_a

So, the Change in total flux linkages will be  = NΦ

Rate of change of flux linkage = NΦ / t

Since flux is changed at two instants so by taking derivative on right side of equation we get rate of change of flux linkage = NdΦ/dt

According to Faraday’s law of electromagnetic induction rate of change of flux linkage is equal to emf.

So get

E= NdΦ/dt ---- (i)

Where flux Φ in Weber = B.A ----- (ii)

Where, B = magnetic field strength

A = area of the coil

Methods of increasing Induced EMF in a Coil

From equation (i) and (ii) we see that Induced emf depends upon Number if turns of coil(N), Magnetic field strength, area of coil. Now to increase Induced EMF following all above three parameters should be increased or decreased as per description below:-

(a)          By increasing magnetic field strength, which in represented by B in formula. Now we see that by increasing magnetic field strength flux increases and this will leads to increase in induced emf.

(b)          By increasing No. of turns of coil induced EMF get increased as induced EMF is directly proportional to Number of turns of coil.

(c)          By increasing area of coil flux linkage with coil get increased so induced EMF get increased.

(d)          There is fourth method of increasing the induced EMF i.e. by increasing speed of relative motion between coil and the magnet, As increase in relative speed will cause to cut more lines of flux at faster rate and EMF produced get increased.

Faraday’s laws applications:-

Faraday law of electromagnetic induction is applicable on most of electrical systems and Transformers, Induction Motors, generators, Induction coils all works on Faraday’s law of electromagnetic induction.

  

Cable size and current carrying capacity

Cable size and current carrying capacity for XLPE insulated cable, non-armored, Twin or multicore cable is as below:-

Conductor operating temperature is 90 degree Celsius

Ambient temperature: 30 degree Celsius.

Cable size and current carrying capacity for XLPE insulated, Armored, Twin or multicore cable is as below:-

Conductor operating temperature is 90 degree Celsius

Ambient temperature: 30 degree Celsius. For air and 20 degree Celsius for ground for installations require to comply with BS: 7671

Correction factors:-

For Ambient temperature:

Ambient temperature in degree Celsius	Correction Factor
25	1.02
30	1.00
35	0.96
40	0.91
45	0.87
50	0.82
55	0.76
60	0.65
65	0.58
70	0.50
75	0.41
80

Ground Temperature

Ambient temperature in degree Celsius	Correction Factor
10	1.07
15	1.04
20	1.00
25	0.96
30	0.93
35	0.89
40	0.85
45	0.80
50	0.76
55	0.71
60	0.65
65	0.60
70	0.53
75	0.46
80	0.38

Soil Resistivity

Thermal resistivity Km/W	Rating factor for cables buried in Ducts	Rating factor for direct buried cables
0.5	1.28	1.88
0.8	1.20	1.62
1.0	1.18	1.50
1.5	1.10	1.28
2.0	1.05	1.12
2.5	1.00	1.00
3.0	0.96	0.90

For cable selection chart for motors visit:-
http://electrialstandards.blogspot.in/2015/10/cable-selection-chart-for-motors.html

AC motors current Rating Chart

Induction motors are part of every industry and Household. There are motors available from fraction of KW to 375 KW motors.
Induction motors are also available with higher ratings but those are HT motors.


AC Motors current rating chart for induction motors is as given below:-

KW Rating	Horse power rating	Three Phase (415V Supply)	Single Phase 220V Supply
0.1	1/8	0.4	1.6
0.12	1/6	0.5	1.9
0.18	1/4	0.7	2.3
0.25	1/3	0.9	2.9
0.37	1/2	1.3	3.9
0.56	3/4	1.6	5.5
0.75	1	1.8	7.3
1.1	1.5	2.6	10
1.5	2	3.4	13
2.2	3	5	19
3	4	6.5	24
3.7	5	8	27
4	5.5	8	30
5.5	7.5	11	41
7.5	10	15	55
9.3	12.5	18
10	13.5	20
11	15	22
15	20	28
18	25	36
22	30	39
30	40	52
37	50	69
45	60	79
55	75	96
75	100	125
90	125	156
110	150	189
130	175	224
150	200	255
185	250	403
225	300	482
260	350	560
300	400	636
335	450	711
375	500	786

AC current rating chart is for 3-Phase power supply and Single Phase power supply.

AC motors current rating chart for 1-phase induction motors is upto 7.5 KW as above this rating of motor at single phase will have a very big size.

Above AC motors current rating chart is at 50HZ supply frequency.

Cable selection chart of above motors is below:-

http://electrialstandards.blogspot.com/2015/10/cable-selection-chart-for-motors.html

Cable Selection Chart for motors

Cable selection chart for motors (Induction motors) for 3-Phase power supply is as below:-

Motor rating on KW	Full load current of motor	Main Cable Size requirement
0.06	0.21	1x3 CoreX1.5mmSq copper cable
0.09	0.32	1x3 CoreX1.5mmSq copper cable
0.12	0.38	1x3 CoreX1.5mmSq copper cable
0.18	0.58	1x3 CoreX1.5mmSq copper cable
0.25	0.7	1x3 CoreX1.5mmSq copper cable
0.37	1.1	1x3 CoreX1.5mmSq copper cable
0.55	1.3	1x3 CoreX1.5mmSq copper cable
0.75	1.8	1x3 CoreX1.5mmSq copper cable
1.1	2.4	1x3 CoreX2.5mmSq copper cable
1.5	3.2	1x3 CoreX2.5mmSq copper cable
2.2	4.5	1x3 CoreX2.5mmSq copper cable
3	5.9	1x3 CoreX2.5mmSq copper cable
3.7	7.3	1x3 CoreX2.5mmSq copper cable
4	7.7	1x3 CoreX4mmSq copper cable
5.5	10.5	1x3 CoreX4mmSq copper cable
7.5	14	1x3 CoreX4mmSq copper cable
11	20.5	1x3 CoreX6mmSq copper cable
15	27	1x3 CoreX10mmSq copper cable
18.5	33	1x3 CoreX16mmSq copper cable
22	38	1x3 CoreX16mmSq copper cable
30	52	1x3 CoreX25mmSq copper cable
37	64	1x3 CoreX35mmSq copper cable
45	78	1x3 CoreX50mmsq copper cable
55	97	1x3 CoreX50mmsq copper cable
75	132	1x3 CoreX70mmsq Copper cable
90	156	1x3 CoreX95mmsq copper cable
110	187	1x3 CoreX120mmsq copper cable
132	221	1x3 coreX150mmsq copper cable
160	260	1x3 CoreX185mmsq copper cable
200	330	1x3CoreX 240mmsq copper cable
250	415	1x 3CoreX400mmsq copper cable
315	520	2X3CoreX 300 mmsq copper cable

Above chart is for copper cables.

If there is requirement for aluminum cables then same will be increased by 1.5 times that the size of copper cable.

Cable selection chart for motors is for 3-phase , 415V at 50 HZ frequency.

For checking motors rating and Motor rated current visit:-
http://electrialstandards.blogspot.in/2015/10/ac-current-rating-chart.html

For cable size and current carrying capacity visit:-
http://electrialstandards.blogspot.com/2015/11/cable-size-and-current-carrying-capacity.html