> EVERYTHING TO KNOW  ABOUT ELECTRIC MOTORS

m bond pumps – a division of m bond engineering pty ltd

> EVERYTHING ABOUT ELECTRIC MOTORS

m bond pumps – a division of m bond engineering pty ltd

What you need to know – HOW ElectricAL Motors WORK

According to a 2022 wikipedia motor article on electric motors, approximately 800 million motors were produced and sold into various market sectors globally. Thats alot of new equipment, being born into the world, every year. If you are in the market for an electrical motor, view our electric motor price list here. 

It is estimated that that a middle sized home has at least 27 AC or DC electric motors, hiding in various places. You’ll find motors in kitchen sinks, vacumn cleaners, compressors, lawn mowers, blenders, pool pumps, cake mixers, garage doors, leaf blowers, vehicles and  in chain saws to name but a few. 

Where would the world be without these rotating machines? While we are surrounded by them, reletively few people really know how they work. We explain the difference between AC and DC motors? 

Gif showing how an electric motor works at m bond pumps

the difference between an AC / DC  EXPLAINED on things which turn…

It is fascinating to know that Direct current (DC) devices work in the same principle as alternating current (AC) motors. However, DC devices use a clever trick allowing them to rotate even if the incoming current is not “alternating”.

All rotating machines work because the direction of current reverses (alternates) every half cycle, causing the armature (shaft) to rotate. You may ask yourself why the current has to swap (alternate) to facilitate rotation. To answer this, the left-hand-motor-rule will explain the relation later.

DC Alone Doesn’t Rotate 

A DC device will only turn if the current direction changes, although DC current supply is unidirectional. The key here is the commutator. This clever mechanical invention allows the current in a conductor to reverse its direction over and over again.

50 Hz AC vs 60 Hz AC

An AC current supply means the direction of current is reversing every half cycle, about 100 times a second if it is a 50 Hz supply, as in South Africa. In the USA, the supply current reverses 120 times per second because its supply is 60 Hz.

DC Doesn’t Change Direction 

DC means the incoming current maintains the same direction. For any shaft to rotate, the current direction must change. This is because the direction of current and the direction of motion of the conductor are related – Introduce Fleming’s left-hand rule.

flemings left hand rule for motors at m bond pumps

the TWO main Types of electric motors, AC and DC

Referring to the Fleming hand rule picture shown above, you can work out the direction of motion of the conductor. Look at the DC diagram on the right; each single slip ring is connected to a conductor. By taking one conductor for reference, the green conductor, which is horizontal on the diagram, has say reached the top or vertical position. This position of motion is indicated by your thumb in the picture on the top left.

Permanent Magnet Fields 

The field provided by permanent magnets in a DC electrical unit is constant, and its direction will always be from North to South, as indicated by your index finger.

Fleming’s Rule in Action

Now attempt to keep your index finger pointing in a fixed direction, I.E., in the magnetic field direction, but change your middle / current finger from pointing towards you to pointing in the opposite direction, indicating the current direction change.

You should notice that your thumb will point downwards, which means the conductor is moving from top to bottom, which is why a conductor must have currents that change direction when the upward motion is complete.

Current Cycle Reverses 

The green conductor would have stayed at the top of the current direction hadn’t changed. Similarly, if you are considering an AC electrical unit, the current cycle reverses at that same instant, so you have your conductor moving down. Through repetition, you have rotation, and the motor turns.

In a DC electrical unit, one has a current that remains in the same direction even after the conductor has moved half a rotation, and this is where the commutator comes into play.

Commutators Explained 

The commutator is a split ring that touches the opposite polarity (+ or -) of the DC supply at the precise moment when its direction must change. Hence the green conductor will receive a current whose direction is opposite because the ring will switch from a brush of, say, a positive polarity to a brush of a negative polarity.

Look at the line diagram and look how one conductor gets both positive and negative currents in a full 360 degree rotation. 

how does an electric motor work at m bond pumps
electric motor magnet gif how it works

WHAT ARE THE KEY COMPONENTS OF  AN INDUSTRIAL ELECTRICAL MOTORS?

Industrial motors used in industry are usually always AC, and are commonly referred to as induction motors. Alternating or AC units don’t have a commutator, and neither do they use ” brushes “.

The key components of induction units are the rotor or shaft, which is the rotating mass -with a protruding shaft- onto which drivers or users are coupled.

With all electrical motors, the rotar ” rotates “, guided by a drive end bearing and a non-drive end ball bearing.

The unit’s bearings are located in motor end shields, which are centrally positioned in the squirrel cage, known as the motor stator.

On the non-drive end, a rotaitng finned cooling fan is keyed, protected by a fan cowling. If you are in the market for an electrical motor, view our electric motor price list here. 

parts of a motor shown in a gif at m bond pumps

ELECTRICAL FRAME SIZES, SHAFT SIZES, OUTPUT POWER, TORQUE, WEIGHT TABLES for 2 Pole Motors

>MOTOR SELECTION GUIDE 2 Pole.pdf

Click on any motor below, for product page, or view our electric motor price list 

Output kW Size

Speed r/min

RPM

Poles Shaft Size mm Weight Kg Current
@ 400 V
Current
@ 525 V
Torque Nm
0,75 80 2800 – 3000 2 19 16 18 14 25
1,1 80 2800 – 3000 2 19 17 26 20 37
1,5 90S 2800 – 3000 2 24 22 34 26 50
2,2 90L 2800 – 3000 2 24 25 49 37 74
3 100L 2800 – 3000 2 28 33 63 48 100
4 112M 2800 – 3000 2 28 45 81 62 132
5,5 132S 2800 – 3000 2 38 64 110 84 181
7,5 132S 2800 – 3000 2 38 70 149 114 247
11 160M 2800 – 3000 2 42 110 213 162 359
15 160M 2800 – 3000 2 42 125 288 219 489
18,5 160L 2800 – 3000 2 42 147 347 264 603
22 180M 2800 – 3000 2 48 180 410 312 742
30 200L 2800 – 3000 2 55 240 555 423 971
37 200L 2800 – 3000 2 55 255 679 517 1 198
45 225M 2800 – 3000 2 55 309 823 627 1 447
55 250S 2800 – 3000 2 60 403 1 010 770 1 768
75 250M 2800 – 3000 2 60 544 1 340 1 021 2 412
90 280S 2800 – 3000 2 65 620 1 600 1 219 2 894
110 280M 2800 – 3000 2 65 632 1 950 1 486 3 537
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ELECTRICAL FRAME SIZES, SHAFT SIZES, OUTPUT POWER, TORQUE, WEIGHT TABLES for 4 Pole Motors

>MOTOR SELECTION GUIDE 4 Pole.pdf

Click on any motor below, for product page, or view our electric motor price list 

Output kW Size

Speed r/min

RPM

Poles Shaft Size mm Weight Kg Current
@ 400 V
Current
@ 525 V
Torque Nm
0,37 71 1300 – 1500 4 14 16 11 N/A 27
0,55 80 1300 – 1500 4 19 17 16 12 38
0,75 80 1300 – 1500 4 19 18 20 15 52
1,1 90S 1300 – 1500 4 24 22 29 22 75
1,5 90L 1300 – 1500 4 24 27 37 28 102
2,2 100L 1300 – 1500 4 28 34 52 40 148
3 100L 1300 – 1500 4 28 38 68 52 202
4 112M 1300 – 1500 4 28 43 88 67 265
5,5 132S 1300 – 1500 4 38 68 118 90 365
7,5 132M 1300 – 1500 4 38 81 156 119 497
11 160M 1300 – 1500 4 42 123 223 170 716
15 160L 1300 – 1500 4 42 144 301 229 981
18,5 180M 1300 – 1500 4 48 182 365 278 1 202
22 180L 1300 – 1500 4 48 190 432 329 1 429
30 200L 1300 – 1500 4 55 270 576 439 1 610
37 225S 1300 – 1500 4 60 284 699 533 1 985
45 225M 1300 – 1500 4 60 320 847 645 2 904
55 250S 1300 – 1500 4 70 427 1 030 785 3 549
75 250M 1300 – 1500 4 70 562 1 400 1 067 4 839
90 280S 1300 – 1500 4 80 667 1 670 1 273 5 768
110 280M 1300 – 1500 4 80 672 2 010 1 532 7 050
132 315S 1300 – 1500 4 85 1100 2 290 1 745 8 460
160 315M 1300 – 1500 4 85 1160 2 727 2 078 10 250
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ELECTRICAL FRAME SIZES, SHAFT SIZES, OUTPUT POWER, TORQUE, WEIGHT TABLES for 6 Pole Motors

>MOTOR SELECTION GUIDE 6 Pole.pdf

Click on any motor below, for product page, or view our electric motor price list 

Output kW Size

Speed r/min

RPM

Poles Shaft Size mm Weight Kg Current
@ 400 V
Current
@ 525 V
Torque Nm
0,55 80 900 – 1000 6 19 16 18 14 58
0,75 90S 900 – 1000 6 24 19 23 18 79
1,1 90L 900 – 1000 6 24 22 32 24 116
1,5 100L 900 – 1000 6 28 32 39 30 152
2,2 112M 900 – 1000 6 28 41 56 43 223
3 132S 900 – 1000 6 38 63 74 56 298
4 132M 900 – 1000 6 38 72 99 75 398
5,5 132M 900 – 1000 6 38 81 129 98 547
7,5 160M 900 – 1000 6 42 118 169 129 738
11 160L 900 – 1000 6 42 145 242 184 1 083
15 180L 900 – 1000 6 48 178 316 241 1 477
18,5 200L 900 – 1000 6 55 200 386 294 1 821
22 200L 900 – 1000 6 55 228 447 341 2 166
30 225M 900 – 1000 6 60 306 563 429 2 923
37 250S 900 – 1000 6 70 419 673 513 3 606
45 250M 900 – 1000 6 70 426 800 610 4 385
55 280S 900 – 1000 6 80 614 993 757 5 350
75 280M 900 – 1000 6 80 635 1 320 1 006 7 230
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>How does a motor work?

Motors change electrical energy into rotating mechanical energy. This is achieved by first converting electric energy to magnetic energy, second converting magnetic energy to a rotational force, making the motor turn.

Copper and Aluminium Windings

Motors use copper and, more recently, aluminium wire windings which are driven by an electrically generated magnetic force exerted by a magnetic field on an electric current.

Put Simply

In layman’s terms, magnetic attraction causes the wound wires to pull and push on each other, creating rotation.

>What is motor?

An electrical motor is a mechanical device which changes electrical current from a power supply, into rotating mechanical energy.

How Big are Electric Motors? 

Units range in size from a few centimetres to several meters in size. Electrical motors can be AC or DC, and are used in millions of different applications globally, constantly.

>What are electrical motors used for?

Motors power anything requiring rotational movement to deliver its intended function.

Where are Motors used? 

Their applications are vast. They are used everywhere and in places you wouldn’t necessarily even know about.

>How to calculate AC electric motor power?

Firstly, power up the unit using either 220v or 380v feed. Secondly, connect a multi-meter in series to each winding, setting your meter to amps. Thirdly, multiply the current on each winding by the rated voltage.

Do the Maths 

Lastly, by adding the results up, you will have the rated power of the electrical motors. Take note of your units, ensure the voltage is volts, the current in amps, and your product of the motor power will be in watts.

>How to generate electricity with motor?

Any electric motor with a permanent magnet can actually be utilised as a generator. By connecting an external power source such as a petrol engine, or wind turbine, to spin the shaft of any permanent magnet electric unit, the motor instantly acts as a generator. 

>How to connect 3 phase motor to 220v?

There are various different methods to connect a 3-phase motor to a single-phase 220v power supply. One way is to use a phase shift capacitor.

Can single phase power a 3 phase unit? 

However, none of the methods come without their disadvantages, and can often be costly and sometimes unreliable. Be prepared also to lose up to 50% of the power’s nominal power rating. It is recommended to use a 3-phase unit with 3 phase power supply or purchase a single-phase unit in the first place.

>What is the best electric motor available in the world?

It is a well-known fact that Zest WEG produces the best electric motors in the world. ZEST WEG motors are the best quality. M Bond Pumps distribute WEG motors. The trusted specialists. Quality motors in stock. Single-phase & 3-phase Zest WEG Units – all you need, & need to know!

>Which type of motor is used in a conveyor?

On the one hand, if your conveyor requires constant control over the direction as well as belt speed, DC units will work best.


On the other hand, if you are requiring a constant speed and uni-direction, then an AC motor is a clear choice. An AC induction motor can be used in an application where the conveyor motor needs to operate always in one direction.

Remember induction motors are reliable and do not have brushes.

Alternatively, when the direction does need to change, consider an AC reversible motor. Lastly, if your belt is running at low speed, with frequent start-stop, consider the low-speed synchronous AC units for the best results.

>Is a household motor a DC motor or an AC motor?

Household motors in South Africa are generally speaking AC motors if they are used to power appliances such as washing machines, fridges, water wells, boreholes, office fans etc. However, DC motors are used in applications such as electric gates, garage doors, computer and laptop fans etc. 

>Which motor is used in toys?

DC Motors are always used in toys, as they are usually 1.2 to 9V DC battery fed.  

>Which motor is best to convert a generator?

A motor with a permanent magnet is best.

Permanent Magnet Generators 

In other words, any electric motor with a permanent magnet can actually be utilised as a generator. By connecting an external power source such as a petrol engine, or wind turbine, to spin the shaft of any permanent magnet electric motor, the motor instantly acts as a generator

>Should I use an AC motor or a DC motor?

You should use a AC motor if your supply power is alternating current, or you should use a DC motor if your supply power is direct current.

>How to know if my 3-phase motor is suitable for a VFD?

Your electric motor will only be suitable for a variable drive application if it has been rated safe to use with VSD or VFDs.

VSD Safe & Suitable? 

At M Bond Engineering we generally ensure that units over 75kW have special insulated bearings installed, as well as a special shaft earthing device to ground unwanted electrical currents from arcing and causing damage to the motor. Generally on the smaller units, running these on VSDs is problem free.

>What RPM are electric motors the most efficient?

Electric motors are highly efficient at approximately 80% of their rated maximum speed which is known as the electrical motor’s “peak efficiency point.”

Peak Efficiency Point

At slower or faster speeds, the motor efficiency will slightly decrease. It is best to consult with the particular manufacture of your motor to ascertain the peak efficiency RPM point.

>Can electric motors turn both ways?

Clockwise VS Anticlockwise?

Both DC units and AC units can turn clockwise or anticlockwise

>Why is a 3-phase motor better than a single phase motor?

A single-phase motor is not necessarily worse than a 3-phase motor. One needs to understand both motors’ applications, to determine which motor is better for your application. In other words, if require an induction motor for domestic purposes with a 220v power supply, then a single-phase motor is the best choice.

High Efficiency & Torque 

However, if high efficiency and torque rate are required for your industrial application, then select a 380V three-phase motor.

>How do electric motors produce mechanical energy?

Electric motors produceech manical energy by creating a magnetic field in their copper coils or windings, which causes a magnetic push effect, resulting in rotational mechanical energy. 

>How to calculate electric power of motor?

Firstly, apply Ohm’s Law which states that current through the conductor is directly proportional to the applied voltage, the formula states:

I = V / R

where I – current, in amps (A)
R – resistance, in ohms (Ω)
V – applied voltage, in volts (V)

Secondly, the consumed electrical power of the motor is defined by the following formula:

P(in) = I * V

where P(in) – input power, in watts (W)
V – applied voltage, in volts (V)
I – current, in amps, (A)

Lastly, motors are supposed to do work and 2 factors, define how powerful the motor is, namely the speed and the torque. (Torque is the turning force of the motor).

The output power of the motor is calculated by this formula:


P(out) = τ * ω

where P(out) – output power, in watts (W)
ω – angular velocity, in radians per second (rad/s)
τ – torque, Newton meters (N.m)

>What is an induction motor?

Single-phase units and three-phase units are both examples of induction motors.

An induction motor is the device used most often for a myriad of applications. It is known as an asynchronous motor, as it runs at speeds below synchronous speeds.

Synchronous VS Asynchronous

In any electrical motor, the magnetic field’s rotation speed is called synchronous. The synchronous speed is a function of the number of poles and the frequency of the electric motor.

An induction motor’s speed is below the synchronous speed because the rotating magnetic field (generated in the stator) produces flux with the rotor, which causes the motor shaft to turn.

Magnetic Fields and Flux

The motor RPM can never reach the speed of the magnetic field (true synchronous speed) speed due to the rotor’s lagging flux current versus the stator’s flux current.

It is important to note that a single-phase induction motor is never a self-starting motor, but a three-phase motor can self-start!

There are several types of induction motors:

Three-phase Induction Motor Types

• Squirrel cage induction  
• Slip ring induction  

Single Phase Induction Motor Types

• Capacitor start induction  
• Shaded pole induction  
• Single-phase induction  
• Split-phase induction  
• Capacitor start capacitor run induction  

3 Phase Induction  

The reason why a 3-phase induction motor can start by itself is due to the fact that in a 3-phase motor, there are three individual phases at 120 degrees to one another. The shaft rotor moves because of the phase difference in the rotating magnetic field. In each phase L1, L2 and L3, for example, the L1 will move towards an attractive magnetic field, and L2 and L3 will each do the same.

Single-phase Induction  

However, when considering a single-phase motor, the single L1 phase can cause the shaft to turn, but it is not self-starting. This is due to the AC power supply, being sinusoidal in nature, and as a result, it generates a uniform magnetic field. Hence, there will be no torque and thus the motor can’t turn.
This scenario is overcome by splitting the stator windings into two. The first winding is the primary winding and the second is the auxiliary winding which is connected in series with a large capacitor.

Phase Differences

This has the effect of producing a “phase difference,“ and hence torque is produced, and the motor turns. If the capacitor is not functional, the single-phase motor will not start, but if aided with a hand turn, it will build up momentum and start.

>What is a universal motor?

A universal motor is a useful electric motor that works on either a DC supply or an AC power supply and usually runs above normal 2-pole speeds. It is sometimes called a “single-phase series motor”.


The motors have changeable speed and their transmitting torque is high. The motors can’t run in a no-load scenario as they will over-run and damage themselves.

Universal Motors Explained 

In a universal motor, the two armature-like-windings and the field are connected in series to produce sufficient starting torque, especially when connected to an AC power supply however, it then also has a lower RPM, due to the reactance voltage drop.

M Bond Pumps stock a wide range of motors with expert advice, quick service and low prices.

  • We are engineers – can we assist you? 
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