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Simple answer is any current carrying cable can cause EMI in an adjacent cable. The "noisier" the source cable is, the greater the EMI. Too provide a quantitative answer, many factors need to be defined. Say on a 22 kV cable, you would need a lot of harmonics to cause EMI.

First, I would assume this is a 3-phase industrial/utility/marine installation, where you may have cables running in trays, racks, or conduit banks; and the conduit is not ferrous. Threaded rigid steel conduit w ...

First, what size of variable frequency drive (VFD) is being approached? When we speak about costs, remember that cost is quite different between a 10 MW VFD and a 7.5 kW VFD. Performances vary as well, in per unit basis and absolute value (kW).

There are also different types of VFDs for different types of motors, that is synchronous or induction for example. Therefore, evaluating case by case makes sense and other considerations along with the above mentioned also needs to be carr ...

If your load requires a motor, say 50HP, then you should use a 50HP motor. The motor is designed to provide the HP required by the load. If you use a higher HP motor you may lose efficiency and power factor (PF).

In general, all the trick is to use smallest motor that is capable to drive the load at 100% duty so its temperature doesn't g ...

Without a ground connection there is potential (excuse the pun) of leakage or wiring fault (or rarely a component fault) biasing the circuit voltage; this is bad because DC control wiring is nominally SELV (safe extra low voltage) and many safety provisions and even component ratings depend on this. I once encountered a problem with unbonded ring wiring (UK) where one phase of 230 AC power was biased to 640 V above ground (exceeded the insulation rating of some equipment). BTW, SELV also has ...

Just a basic analysis if your motor is rated for 30 kW then the rated HP is 40 and actual load on the motor will be 29.5 HP. If the source system is considered stiff then supply frequency doesn't change. Torque varies with the motor terminal voltage squared so the torque being at 75% of motor rating means voltage can be decreased to 87% to have run adequately (assuming slip stays constant).

Reality is that the supply voltage (again system is stiff) will not drop so to compensate sl ...

Flux walking, also known as flux stair casing, is the successive accumulation of flux in a magnetic core ultimately leading to its saturation. In any circuit involving magnetic elements operating in steady state, the net (volt x time) product applied to the core must be exactly zero. If you have more than one piece of magnetics, the volt-second balance must hold for every one of them individually. Voltage polarity should be accounted for and summed over one switching cycle. Even the slightest ...

The Power Factor used to declare power ratings on three phase generators is 0.8 (so 100kVA = 80kWs etc.). Unfortunately the difficulty for installers is understanding the effect of power factors within an electrical installation is a changeable situation dependent on equipment within a load. This is something that the installation engineer needs to understand when specifying a generator for a load and in my experience the best method of evaluating what happens in a load is to test it for a le ...

Using a DOL system is an economic way to start a motor en by the way have cost saving, but for me the only way of really saving money according energy consume is variable frequency drive (VFD), for an easy reason, is that all the system size have a margin error in calculation and the load thermic load point is most of the time different of the real load on site, due to many reason.

I mean that using a VFD help to get the real needed load point of an application and by the way make ...

A Neutral Grounding Transformer is NOT a three phase transformer, but a single phase transformer, with the primary (HV) rated voltage equal to the system phase-to-neutral voltage and the secondary (LV) rated voltage either 110V or 240V.

Why is it required? For economic reasons. Let us see how. Supposing you have an 11kV System, whose neutral you want to ground through a resistance. The desired ground fault current, let us say, is 10A. Now, if you want to connect a resistor directl ...

For the only reason that actually we have on the industrial market enough technology and tools to comply with all process using rotating machine, so actually just having a look to technology is not enough anymore.

And more than this if we build high efficiency product and we talk a lot all around the world of energy saving is not only for fun, but to push people working in technical business like ours to go a bit more deeper than just make something moving and more and more take c ...

For outdoor use could be many different specs and enclosure accessories, starting with Nema 3R enclosure up to Nema4X, but the correct enclosure spec depends on temperature, humidity, elevation, corrosion agent, etc. For example you can't use a Nema 3R in a tropical rainforest nearby the sea because of corrosion, but you can use in a high elevation desert with a space heater.

Manufacturers follow commonly the Ingress of Protection against Dust particles and Water. Indoor enclosure ...

Two sided bonding will reduce the induced voltage but increase the circulating current in the cable sheath. This circulating current will cause heating to the cable and reduce its maximum ampere rating. Single point bonding can be done but there may be high induced voltage present on the floating non-earthed end. However, there is a benefit in the fact that there will be no circulating current in the cable which improves the cable's ampere rating.

This is why for long cable circui ...

A single phase motor is nothing but an AC electro magnet. In order to spin the rotor we need a rotating electric field. By adding two more coils and a capacitor to cause phase change we get two magnets and a time delay between their cycles - like magic we have a rotating field.

Many parameters of inductance, resistance and capacitance need to be optimized for high efficiency. Once the motor is up close to synchronous speed some designs switch out the second set of coils with a cen ...

I am in the sugar industry and our factories tend to be very close to nowhere. We have large energy demands which we meet with a renewable fuel but we do have "brown outs" and short duration "blackouts" aside from the total "blackout" situation. If this is not what you require, stop reading now.

We have recently started introducing "ride through" to many of our critical applications. If the factory is stopped it is very difficult to get going again and the losses are high. The mos ...

If you know your load is exactly 40 Hp, never higher, then it's best to use a motor that's rated for 40 Hp. The nameplate rating of a motor means that is where it was designed to run most efficiently. If you use a higher Hp motor than you need, you will just be running somewhere in the lower part of it's speed-torque curve. Your efficiency will not improve if you use a 100 Hp motor but only load it to 40 Hp.

Also, many motors have a service factor of 1.1 or 1.25. If it does, then ...

The process is the same for any "smart device" development and based on the common principle of "measure some parameters via sensors or transducers - do some maths on the values measured - then initiate some designed for action in response". The cycle then repeats itself continuously. How easy is that?

In another form a "smart device" can be one that uses feedback from inputs to build up enough semi intelligence to operate in a feed forward state of mind. Let me explain this point ...

The excitation system requires a very small fraction of the total power being generated. If we could simply increase the excitation (a very small amount of power) and increase the generator's real power output, the world's energy problems would be solved, because we would have a perpetual motion machine.

In the case of a generator connected to a large grid, the generator will inject any desired amount of power into the grid if its prime-mover is fed the desired power (plus a small ...

The main breaker should be sized ad 150% of the motor Full load current, the overload should be sized at 115% or 125% of the Full load current that depends on the service factor. You conductors can be sized at 125% of the motor full load current, and the contactors can be sized at 58% of the motor full load current for the main and delta contactors and 38% for the star contactor.

Normally I would just use contactors of the same value but some engineers use that calculation. Reason ...

This discussion has touched upon three topics that are each independent from the others.

1. Asymmetry due to only one or two phases being faulted
2. Asymmetry due to a DC offset of the sinusoidal fault
3. The decay of fault current with time due to differences in the reactance of generators with time (not really an asymmetry and not addressed by my comments)

The negative-sequence vectors do not rotate in the opposit ...

Distributed generation generally means more than one power source feeding the same loads including sources at multiple locations but it can also mean stand alone or isolated generation at the point of use. Typical for this definition are generator and UPS at mission critical sites such as data centers and laboratories. These can operate in complete isolation, in parallel with the utility grid, in parallel as part of a local grid. Power can also be transferred between the utility grid and loca ...