This issue can be resolved by adjusting the tap position so as to get required output voltage. It is also important to bring up the issue with your utility supplier (NEA).

The issue should be brought up with your utility supplier. In the meantime the issue could be resolved by installing a voltage stabilizer / regulator.

The reasons could be many but is important to understand the difference of Voltage drop and voltage loss – Generally longer your runs (distance between DTR and DB), the lower the voltage at the point of utilization. But not all of the difference may be due to voltage drop. Voltage drop is not caused by poor connections, bad contacts, insulation problems, or damaged conductors; those are causes of voltage loss. Voltage drop is a fixed condition; voltage loss is nearly always a deteriorating one. This means if you measure a voltage differential greater than the voltage drop, you should find what is causing the additional amount (unless it’s only a volt or two). The higher the voltage, the more likely you have one or more connections moving toward failure. A good first step is to get out the infrared camera and check all connections on this run. Then disassemble and replace any bad ones (don’t just “retighten” as that will only make things worse by reducing the clamping power of the fasteners). If you still measure more than a volt or two above the calculated voltage drop, further troubleshooting is wise.

You might, for example, look at the contact resistance across safety switches, contacts, fuses, and circuit breakers. Any of these can produce a voltage loss. And if it’s in one place, it is likely in another (for the same reasons it exists in the first) so don’t stop with the first one you find and think you found “the problem.”

The reasons could be many starting with 

1. The cable selection type being improper, causing the conductor cross section of the cable to be used to be too small, and an overload phenomenon occurs during operation. After a long time of use, the heat generation and heat dissipation of the cable are unbalanced to cause heat generation.

2. When Loads are unbalanced over the three phases

3. The cable arrangement is too dense, the ventilation and heat dissipation effect is not good, or the cable is too close to other heat sources, which affects the normal heat dissipation of the cable, and may also cause the cable to generate heat during operation, 

4. Contacts are not proper like, crimping is not tight, and the contact resistance at the joint is too large, which may cause the cable to generate heat, 

5. The partial sheath of the armoured cable is damaged. After the water enters, the insulation performance will be slowly destructive, resulting in a gradual decrease in the insulation resistance, which will also cause heating in the cable operation.

Transformers play a key role in any electrical distribution network. Electrical transformers transfer electrical energy from transmission to distribution systems by raising or lowering voltage levels. This transmission usually occurs over long distances, typically greater than tens of kilometers, so the transformers must not only be able to handle the primary voltage (thousands of volts), they must also be able to withstand the voltage drop over long distances.

As a transformer is an integral component of the electrical system, it requires proper monitoring and maintenance. Transformers overheating can lead to damages in the internal windings, insulation damage, and fire.

The main causes of power transformers overheating include,

1. Overloading

2. Unbalanced load causing over current in one or more phases

3. Exceeding the ambient temperatures

4. Overvoltage or under voltage

5. Issue in transformer fans, Insufficient cooling or failure of cooling system

6. Damaged insulation material

7. Short circuit between core and coil

8. Harmonics

9. Oil degradation/ impurities in oil.

Check Power Factor and add capacitor bank to bring PF to as close to as Unity.

The purpose of a tap changer is to regulate the output voltage of a transformer by altering the number of turns in one winding and thereby changing the turn's ratio of the transformer. Basically what it means to step up or step down the output voltage of the transformer so as to bring it as close as possible to the control voltage.

OLTC – On load tap changer

NLTC – No Load tap changer

As the name suggests in and OLTC you can change the tap position while the transformer is in service while as in case of NLTC you must isolate the transformer to change tape tap position. It is advisable to buy an OLTC where you are not very confident regarding supply voltages. If you are sure that voltage is stable it may be advisable to buy a NLTC due to cost benefits,

This question will be very difficult to explain to somebody who does not have theoretical knowledge. The question would be better worded – 

“How does installing a capacitor bank help?”

In Nepal there the billing from the utility is structured as a two part billing. a) Energy (kW) and b) demand (kVA). In many countries there is kVA billing and in some there is a penalty for low power factor.

To understand this a commonly used example is a beer glass analogy. Generally speaking when beer is served in a glass it has two parts the liquid which is the useful part and foam which is not useful. When we pay for a glass of beer we think we are paying for the liquid part (beer) but actually we are paying for both i.e. liquid and foam which is not what we drink. Similarly when we consume energy it has two parts. The real energy (kW) and the apparent energy (kVA). By installing a capacitor bank in the system what we try to do is bring down the apparent energy as close as possible to the real energy. It’s like reducing the foam in the glass of beer so that the glass has only liquid to the brim.

Short answer:

Size of Over current protective devices = 100% of non-continuous load + 125% of continuous load.

Detail: 

MCB is faster in detecting the overcurrent than fuse. 

The MCB detects the excess current flow and immediately breaks the circuit which can be seen as tripping action of the MCB knob. Previously, this job was done by fuse. 

Circuit breaker (CB) is designed and evaluated to carry 100% of its rated current for an indefinite period of time under standard test condition. 

Size of Over current protective devices = 100% of non-continuous load + 125% of continuous load.

Continuous load = load that runs for more than 3 hour

Example 1: Size MCB for 50 A continuous load and 125 A non-continuous load 

                = (1*125) + (1.25*50)

                = (187.5 A)

Recommended, a 200 A size. 

Example 2: 200 A Continuous load 

                   = (1*0) + (1.25*200)

                   = (250 A)

Miniature Circuit Breaker (MCBs) is an automatically operated electrical switch which is designed to protect an electrical circuit from damage caused by excess current from an overload or short circuit. 

Advantages:

Handling MCB is electrically safer than handling a fuse.

MCB is reusable and hence has less maintenance and replacement cost. 

1. Working of power factor and capacitor bank? leading or lagging 

• Short:

The angle (cosine) between voltage and current is called power factor.

In Nepal the standard voltage is 230 V and the frequency is 50 Hz. (some countries like U.S and Canada are 110-120 volts/60 HZ)

50 Hz means in 1 second 50 cycle cross in waveform, Voltage cycle remain constant whereas current cycle depends on how much current flow through the circuit. 

• Details:

   Voltage and current waveform

To understand types of power factor first we need to understand types of load

1. Resistive load 

2. Inductive load 

3. Capacitive load 

Resistive load: Here voltage and current waveform crosses together at zero degree. i.e. no phase angle difference between voltage and current. 

Power factor is unity in resistive load.

θ= 0º

Cos (θ) = Cos (0)= 1 

Inductive load: here, Current lag behind the voltage then power factor refers as lagging power factor.

θ= 36.8º

Cos (36.8) = 0.8

Capacitive load: here, current leads the voltage then power factor refers as leading power factor. Normally there is no capacitive load except capacitor bank. 

Reactive Power: if the reactive power % is more the system efficiency will be poor. So as the power factor. Reactive power comes from Inductive load. 

now, to improve power factor 1st thing one have to do it to reduce reactive power percentage which can be done by installing capacitor bank as capacitor bank produce leading power factor and this will compensate each other. 

Talking about Voltage stabilizer, it is used as it acts as a safe guard between your equipment and utility by continuous monitoring and stabilizing the voltage fluctuation that appears in the utility. Voltage stabilizer either step up or step down to required voltage for the plant utility.

Now, coming to answer to your question, the first thing is to know your load rather than size of the transformer, normally plant load is lower than the size of the transformer. For example, if someone have installed transformer of 1000 KVA and his plant load is 500 KVA than the proper recommended size to purchase would be 500 KVA plus 20-25% safety margin incase if you want to add more device later. Things to be considered before purchase;

1. Determine input voltage for the equipment to be protected

2. Determine rated amp or kw for the equipment to be protected

3. Multiply the voltage by the current by 1.732 and divide by 1000 to obtain the size rating in KVA. (V*A*1.732/1000).

Time of Day (TOD), you normally pay different rates for the use of electricity for different timing. 

3-different rates and its times

As you can see off peak hour rates is nearly half when compared to peak hour, therefore it is always beneficial to run water pump or any other electrical appliances which is just used for few hour during off peak hour. Most of the steel plant whose market demand is less they normally operated during off peak hour to reduce the cost of production. 

Notes- cost of energy increases or decreases depending on province rates, feeder supply and yearly season. 

My TOD meter unit consumption is exactly same as previous month, is that possible?

Unit consumption cannot be exactly same for two different months, there can be few things you have to look on;

1. TOD meter sometimes it get freeze and exact values is on electricity bill

2. It can be mistake with meter reading 

3. Look for replacement of TOD meter

Here again one must understand the function of the capacitor bank. What it actually does is stores energy to be released so as to phase balance the current and voltage. By installing a capacitor bank in the generator circuit could lead to over loading of the generator where by effecting the performance of the generator.

This question will be very difficult to explain to somebody who does not have theoretical knowledge. The question would be better worded – “How does installing a capacitor bank help?” In Nepal there the billing from the utility is structured as a two part billing. a) Energy (kW) and b) demand (kVA). In many countries there is kVA billing and in some there is a penalty for low power factor. To understand this a commonly used example is a beer glass analogy. Generally speaking when beer is served in a glass it has two parts the liquid which is the useful part and foam which is not useful. When we pay for a glass of beer we think we are paying for the liquid part (beer) but actually we are paying for both i.e. liquid and foam which is not what we drink. Similarly when we consume energy it has two parts. The real energy (kW) and the apparent energy (kVA). By installing a capacitor bank in the system what we try to do is bring down the apparent energy as close as possible to the real energy. It’s like reducing the foam in the glass of beer so that the glass has only liquid to the brim

No it is not, normally when motor is operated in poor or dusty environment or motor cooling fans are removed the motor tends to heatup.

Causes of Electric Motor failure:

• overload on motor

• short cycling 

• Voltage imbalance (a three percent voltage imbalance can cause an 18 percent temperature rise in the motor)

• Environmental Condition

• Misalignment between motor and load. 

• Improper lubrication (grease in winding)

• moisture and dust 

Short:

Normally, motor is a device that convert electrical energy to mechanical energy.

While a servo, usually is a normal motor is equipped with accessory control electronics (encoder and driver) so it can move to and hold a certain commanded shaft position (some servo systems support speed and torque also).

Details:

The terms "servo" implies that there is a feedback loop which adjusts one or more operating parameters of the motor such as velocity, position or torque. Servomotor are used in closed loop system where accuracy and repeatability are important. 

Whereas, regular motor (without feedback) are run "open loop" where positional accuracy is not an important factor.

Overload protection in motor is important to prevent motor against excessive currents that would cause overheating of the motor. It is basically a safety protection like a fuse or a breaker that prevent motor from getting damage

Answer is yes. In fact, if you can design your device to run motor slower (lower than nominal voltage) this is a very good thing. Running at lower voltages means lower speed, means less brush types motors, lower current consumption and longer motor life.On the other hand, if size restrictions and performance requirements demand additional torque or speed, overdriving the motor is possible. However, you must be willing to sacrifice product lifetime if you over drive the motor.

Basically, it is energy efficiency levelling represented for motor, like a star levelling. The energy efficiency of an electric motor is calculated as the ratio of the mechanical output power to the electrical input power. The energy efficiency level is expressed in International Energy efficiency classes (IE), IE1 being the lower class and IE5 the highest. Under the current regulation, motors must reach the, IE3 or IE4 efficiency level depending on their rated power and other characteristics. For instance, three-phase motors with a rated output between 0.75kW and equal to or below 1000kW must reach the IE3 level by 2021. Motors between 75kW and 200kW must meet the IE4 level as of July 2023. The EU is the first place worldwide making the IE4 level mandatory for some categories of motors.

It's just a myth, unlike discharge lamps, LEDs are semiconductor and their life span is not affected by the number of times they are turned ON & OFF.

LEDs are inherently low voltage devices and require driver. However, many LED products in the market come with built in driver and hence can be directly connected to the main voltage.

LEDs product does not fail suddenly when compared with conventional lighting. Instead, the light output reduced over the time which is also known as lumen depreciation.

There can be several reason a rise in your bill amount, which generally aren't taken into account by a majority of people.

Faulty wiring: Faulty wiring not only increase your bill but it can also damage the appliances in the long term, lead to electrical fires or even get electrically charged that can cause electric shock to human being.

Defective Wiring: Damaged electrical wire can cause the connected appliances to heat up and consumed extra electricity. A situation like this calls for an inspection by a licensed electrician right way.

Old Wiring: Old wiring can cause fire hazards with increase in risk factor.