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For a 3 phase induction motor, say rated 110 kW, that uses to drive a high inertia centrifugal fan. If we stop the motor, the induction motor still rotates due to load inertia. So is it harmful to run the induction motor again while it's running by load inertia?
Induction motor for centrifugal fan
This will lead to induction generation. Voltage will be induced in stator. Now ...

Besides of the different frequency of 50Hz and 60Hz power system, European/Asian single phase 3wire 220v-240v (L,N,G) is different with American split phase 4wire 120v/240v (L1-L2,N,G) power supply. GoHz frequency converter is a great solution to convert between 50Hz and 60Hz to make the appliance work at its rated frequency among different countries, the input accepts both single phase 3wire 220v-240v and split phase 4wire 120/240v system, also the output terminals can be selected for either ...

Electrical equipment has a design operating point. The data for this (volts, amperes, frequency) and other things such shaft output power and speed, for example, for a rotating machine help define the operating envelope.

RATED voltage is the voltage on the nameplate - the "design point" for maximum power throughput and safe thermal operation. OPERATING voltage is the actual voltage applied at the terminals to the electrical equipment.

For example - a machine has a rated ...

The efficiency of the induction motor can be improved by controlling the air-gap flux. The flux level varies with load torque i.e. at light load torque the flux required is less than the flux required as the load increases. When the motor is operating at a particular operating point defined by speed and torque, an infinite pair of impressed voltage/frequency can achieve this operating point. However only one particular pair of voltage/frequency will result in the minimum losses and maximum ef ...

GoHz Frequency Converter is a specialized AC power source to simulate worldwide electric power to make your appliances work in its perfect circumstance. By installing GoHz frequency converter, you can bring American 60Hz machines (for both single phase and three phase machines) to be operated well in European 50Hz electric power, vice versa, or even get 400Hz output for aircrafts.

This article will show you the basic wiring/com ...

For the past 40 years most industrial facilities operating between 480V and 5kV were designed with 3 phase 4 wire systems. This addressed the concern over transient over-voltages and allowed for neutral loads but these loads are typically 10% or less of the total load and designing a 4 wire system just to accommodate single phase loads adds cost. In addition to higher cost there is higher risk as 4 wire solidly grounded systems have the highest probability of arc flash. Designing a 3 phase 3 ...

USA/Canada single phase 240v power source consists of 4 lines, named L1, L2, N, G
L1-N = 120V, L2-N = 120V, L1-L2 = 240V
Even though GoHz single phase frequency converter can be made for 120v input, it will require additional auto-transformer inside the frequency converter to boost the voltage from 120v to 240v which will increase the weight of the converter along with the total costs.

Generally, GoHz ...

High quality power supplies are essential in the R&D and production lines of electrical and electronic manufacturing companies. Frequency converter is a device to transform a certain frequency (e.g. 50Hz, 60Hz) & voltage AC power into another voltage and frequency power supply, to simulate any power system standards in the world. It's a common device being used for various industries, laboratories and export-oriented electronic manufacturing companies. Calibration is essential for fre ...

Why use a current limiting breaker?
Could those breakers be applied to higher short-circuit current than they are rated for?
What is the range of current those breakers should be used and why?
Why some manufacturers offer them while others don't, or maybe they just called it differently?

A current limiting breaker exhibits a current limiting characteristic. That is it can reduce the peak apparent fault current to a lesser value and isolate the fault in less than a half ...

A circuit breaker is more reliable for tripping big machines than a drive. Hence some engineers prefer tripping a machine from the breaker via the PLC/safety controller. The machine could be pump or compressor.

After the trip, the startup means energizing the primary side of the transformer, whose secondary side is connected to the variable frequency drive. This subjects the transformer to the startup inrush current which could degrade it.

Tripping the machine may be due ...

To terminate three single core, 240 sqmm Al/XLP/AWA 33kV cables between two NXPLUS switchgear, as you can see in the attached picture, it has rubber sleeves at the cable entry, is it better to use brass glands instead, in order to keep the armor connected to earth, or this is not advisable?

The gland has two functions. It is to act as a transition point for the cable to allow it to remove the protective insulation and the second is to fix it so that in the event of a fault, it doe ...

Assumption: Generator Xd''=0.20, Xs=1.5 pu.
Now, Generally Speaking if we speak of bus fault at generator terminals we say fault current =1 (pu voltage)/0.20= 5 pu. Similarly fault current after 5 seconds or so =1/(1.5)=0.66 pu.

1) The concern is that 1 pu voltage assumed is generator open circuit terminal voltage. So internal voltage generated by machine is 1+(armature current(phasor)*reactance(phasor)). This value reaches up to 1.5-2 times the terminal voltage. All the reac ...

Q: We have a 2250HP Synchronous motor used for compressor application. It was observed that IR value in on phase was very low0.007 while the rest of the phases were about 50 Mohms. We cleaned the stator with solution, heated the windings to approx. 60deg. But even then faulty phase did not show an improvement in IR. Although rewinding seems to be an option, what needs to be done to pin point the fault?

A: When working with motors or xmfrs, especially MV, you need a megger/IR tester ...

A number of things would cause a transformer to run hot; if you load it continuous 95-100% which is not good practice, solution-install bigger transformer if cannot permanently reduce load. Transformer winding temperature is measured indirectly unless your transformer has fiber optic sensors embedded in the winding.

Never re-energize a transformer that has tripped on Over Pressure (Dev 63) without first performing IEEE routine test on the transformer. Most oil filled transformers ...

I am in the process of designing a harmonic filter for a client and to tell the truth, if you never done this before, it is much more complicated than it seems.

You have to know if the source of harmonic is a voltage or current source. The best is to know the equipment generating them and be able to estimate precisely the amount of harmonic present in the system. If you are lucky it is a current source and you may wish that your filter will not change the amount of harmonics. Then, ...

To properly answer this question, we would need to have the actual motor ratings and operating load conditions, I.e.; nameplate voltage, frequency, amperes & service factor. Actual operating conditions would be; operating voltage, operating amperage & type loading (constant, cyclic/constant etc.). Generally, a motor with a nameplate rating of 3ph 230 volts can operate as low as 3ph 207 (+/-10%) system volts. However, if the operating conditions are a heavy load at or near nameplate fu ...

The most common method used by manufacturers is to anneal the electrical steel after the lamination has been punched to its final shape (e.g. the diameters are fixed, the slot geometry is complete, and any "retaining" geometry is complete). Due to the temperatures involved (750 C or so), it is something that is done at the end of the process whereby the lamination is created - well before any actual construction (e.g. stacking) of the stator or rotor begins.

Generally speaking, the ...

In the datasheet of a squirrel cage induction motor, rated stall time- 18/30Sec (cold/hot) & Acceleration time- 9/15Sec (100%/80% of rated Volt) are given. In motor protection, it has stall protection, number of start limitation & thermal overload. Since the motor under subject is driving a fan, it takes longer acceleration time & tripping in thermal overload every time during startup.
1. What is the Acceleration time-9/15Sec given in datasheet? Is it the maximum the motor c ...

Three phase asynchronous AC motor is widely used in industrial and agricultural production due to its simple structure, low cost, easy maintenance and easy operation. 3-phase AC motor uses 3 phase power supply (3 ph 220v, 380v, 400v, 415v, 480v etc.), but in some actual applications, we have single phase power supplies only (1 ph 110v, 220v, 230v, 240v etc.), especially in household appliances. In the case to run the three phase machines on single phase power supplies, there are 3 ways to do ...

Shaft voltage is directly attributable to two different things: dissymmetry in the magnetic path, and generation of a static charge.

Internal to the machine, the construction of the magnetic circuit (laminations and frame) and the layout of the conductors (winding) contribute to a potential dissymmetry in the flux path. After all, most coils are hand-made - which leads to marginal, but noticeable differences.

External to the machine is the source waveform. If it is disto ...