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50 Hertz Industrial Electricity

All of Europe and most of mainland Asia and Africa use 50Hz frequency for their industrial electrical needs. Industrial motors operate better at this frequency, since the voltage drops could be easily maintained.

465 Questions

Why does one pin on a three pin plug get really hot?

Either the conductor connection to that pin of the plug is failing-replace the plug

or- the receptacle is old and loose fitting due to metal fatigue-replace the receptacle

or- the conductor termination at the receptacle is loose-tighten or replace receptacle if damaged. Loose connection creates resistance, which equals heat

Answer for UK and other countries using 13 amp square-pin plug:

I had this happen yesterday in a fused plug and cured the problem by opening the plug, taking out the 13 A fuse and squeezing together the fuse sockets with pliers to make the fuse a tighter fit. Then I put the fuse back in. That did the trick (for a UK 13-amp plug with fuse feeding a 2 kW convector).

Why is the live pin getting hot on a three pin plug?

Heat is caused by a current trying to flow through a resistance. What you have is probably a loose connection on one of your screw terminals of the plug creating a higher than normal resistance. Take a screw driver and tighten the screws and see if that makes a difference.

What is the basic function of PLC?

PLC or programmable logic controller is a digital computer used for automation of electromechanical processes, such as control of machinery on factory assembly line, amusement rides, or lighting fixtures.

How can you calculate the current carrying capacity of 1 sq mm wire?

4amps can pass in 1sqmm of wire max it is universal.

In the UK 1 sq. mm wire can take 10 amps max according to tables. Cables that become warm in use should be replaced by a thicker gauge.

What are the methods to calculate and improve power factor?

The best way to improve power factor is by adding capacitors. Low power factor is due to reactive loads (motors, pumps, etc.) that are connected to your electrical system.

ADDITION

The best way to improve power factor in the case of motors is to use a motor drive, like a Variable Frequency Drive. These drives allow very precise control over a motor, unlike the very sudden, jerky starting and stopping across the line seen when using a motor starter. They eliminate the huge inrush current required to start motors that causes low PF.

Answer:

1) Power factor can be calculated by connecting an energy meter [P] (voltage coil in parallel & current coil in series with the load), a voltmeter [V] across load and an ammeter [A] in series with the load. Measure P, V & I.

Since, Active Power (P) = V.I.Cosϕ

power factor = Cosϕ = P/VI

2) Power factor is usually (industrially) improved by connecting a shunt (parallel) capacitor bank at feeding end.

How it works??

Inductive loads contain both inductors and resistors. But due to phasor difference of coils and caps when voltage is applied across both, the two currents results in a smaller net current finally. So now the angle (ϕ) between the voltage phasor and current phasor is lessened. When ϕ is reduced, Cosϕ is risen resulting in a higher power factor.

We have a problem with induced voltage. We measure 220 VAC in the L and 45 to 60 VAC in the N. There is no chance of changing the cable. How to avoid this?

Normally the neutral wire of every circuit is connected to the neutral bus bar in the main breaker panel. Because the neutral bus bar is always connected to ground you should never be able to measure any voltage between the neutral wire and ground.

So, if you are measuring 45 to 60 VAC between the neutral and the ground it could be that the neutral wire has become disconnected at the breaker panel or somewhere in between the panel and the point where you are measuring that voltage.

Assuming the load equipment - an appliance, a motor or whatever - is still connected to the hot and neutral wires, then, if there is no connection to the neutral going back to the power station, in effect you are measuring the line voltage from the hot feed as reduced by the resistance and/or reactive impedance (total reactance) of the load. That could be making 45 to 60 VAC, as read by your meter, appear on the neutral wire coming back from the load.

A simple way to prove if that is the case is to unplug or disconnect all loads - appliances, light fixtures, motors, etc. - from the circuit in question. If you cannot then measure any voltage between the neutral wire and ground the next thing to check is the resistance between the neutral and ground.

First of all switch off the circuit by switching off the breaker at the main panel - or remove the circuit's fuse if it has a fuse and no breaker - and then use the resistance range on a multimeter to measure the resistance between the neutral wire and ground. If it is a very low resistance then an open neutral is not the cause of your problem. If it measures as a very high resistance or an open circuit then your problem is an open neutral.

The reason for the open neutral must be found and that fault must then be corrected urgently.

In the Discussion page to this question please let us know what you found when you did the tests suggested above, and whether or not this advice helped you to locate and fix this problem.

To be able to help you better it is important to know exactly here this circuit is located geographically in the world and to have confirmation whether - as inferred from your question - it is a 50Hz system with one 230V live and one neutral or whether it is actually a 60 Hz system having two 120V hots (+120V and -120V) balanced around neutral.

Then, if necessary we shall have to consider what other reasons could cause the fault you have described but to be able to do so it would help to know exactly what you found when you did the tests described above.

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As always, if you are in doubt about what to do, the best advice anyone should give you is to call a licensed electrician to advise what work is needed.

Before you do any work yourself,

on electrical circuits, equipment or appliances,

always use a test meter to ensure the circuit is, in fact, de-energized.

IF YOU ARE NOT ALREADY SURE YOU CAN DO THIS JOB

SAFELY AND COMPETENTLY

REFER THIS WORK TO QUALIFIED PROFESSIONALS.

What is the excitation system in a generator used for?

The excitation system is used to control the excitation of the rotating field in the armature. By increasing the armature current, it in turn increases the magnetic flux in the armature coil. This has the effect of increasing the voltage output of the generator. By lowering the armature current this in turn lowers the generator output voltage. The generator's voltage regulator automatically adjusts the output voltage continuously as the applied load on the generator changes.

How do you connect a single phase motor to a three phase power supply in UK?

for countries in Europe and other world areas running a 50 Hz supply service. UK household AC power mains voltage is now 230V (previously it was 240V) 50 Hz. From a 415 volt 3-phase incoming supply you will get this voltage between any ONE line and the Neutral.

Between any two lines you will get 415V. DO NOT WIRE IT LIKE THIS!

So, if you wire the motor to any ONE line (and ONLY ONE) and Neutral you'll get the correct voltage.

<><><>

As always, if you are in doubt about what to do, the best advice anyone should give you is to call a licensed electrician to advise what work is needed.

Before you do any work yourself,

on electrical circuits, equipment or appliances,

always use a test meter to ensure the circuit is, in fact, de-energized.

IF YOU ARE NOT ALREADY SURE YOU CAN DO THIS JOB

SAFELY AND COMPETENTLY

REFER THIS WORK TO QUALIFIED PROFESSIONALS.

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My advice would be to buy a proper transformer which can be connected to a 415V 3ph input and give 230V 1ph output at a current rating suitable for the motor and its purpose. I assume the questioner's installation is in a commercial premises because domestic supplies in the UK are 230V 1ph only - running a 3ph motor off that requires a suitable inverter.

Which equipments used in the substations?

In a substation there are many items.

Circuit Breakers

Disconnectors

Earth Switches

Current Transformers

Voltage Transformers

Surge Arrestors

Power Transformers

Insulators

Can a 440V motor run on 380V supply?

Providing the Motor has a CE marking on the data plate. This means it has been tested and compliance with European standards.

What are discrete inputs?

Discrete inputs are inputs to a PLC(programmable logic controller)that require an on or off signal. Limit switches,push buttons,selector switches or relay contacts would be good examples of devices used on discrete inputs.Hope this helps.
Inputs often refers to data that is entered into a computer. The resources that are needed for production purposes can also be called inputs. Some of these things are raw materials, energy, and machines, for example. People can also offer their input on a situation. Most people use the word input instead of inputs.

Can you put a 15 amp fuse in an electric fire plug?

I would say no as it could blow and if majorly can damage the plug and can be expensive to repair

1 unit equals how many watts?

The 'unit' is a measurement of energy used in the UK for the purpose of billing consumers, and is short for 'Board of Trade Unit'. An 'unit' is exactly equivalent to the kilowatt hour, a power of one kilowatt running for one hour. You cannot equate the unit (energy) with the watt (power).

Why should a prime mover's speed be kept constant?

As you asked the question and it was added it to the electrical category I am presuming that you are talking about electrical generation. The prime mover has to be kept at a constant speed. The speed of the prime mover governs the frequency of the voltage generated. As the load increases the engine will start to slow down. The engine's speed governor senses this drop in RPM, hence the drop in frequency, and increases the fuel supply to the engine by advancing the diesel engine's fuel rack. This action increases the engine speed and brings the generated frequency back to the required system frequency.

Also as the load increases, the output voltage will start to decrease. The output voltage is controlled by the generator's voltage regulator. When the decrease in voltage is sensed by the voltage regulator, it increases the generator's field excitation voltage which will bring the voltage back to the required system voltage.


These actions are going on continuously, balancing each other all the time the engine is running and the generator is producing an output voltage.

How can I wire a 240 V single-phase outlet from a commercal building with 3-phase service 4- wire?

A three phase four wire commercial distribution service will not give you 240 volts. The nearest voltage you can get is 208 volts. It is a wye connection which gives you 208 volts between the three legs and 120 volt between any of the three legs and ground. This ground point is the systems neutral point.

What is the substation?

The substation is the point in the T&D system at which the generated voltage is either stepped up for transmission or stepped down for distribution. This is accomplished by a large power transformer within the substation. The lower distributrion voltage is carried from the substation on feeder circuits that eventually make their way to the smaller pole-mounted or pad-mounted transformers that we see in our neighborhoods. These transformers further step down the distribution voltage (normally 12kv) to the useable 240/120 volts that we use in our homes.

What is cable size for a 75kW 3 phase 415V Induction Motor 15 meter run of cable started direct-online?

For an answer please state the full load amps of the motor at 415 volts. Cable sizing is based on the amps the cabe has to handle.