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A few years ago I wrote an article listing the things that can often fail in power supplies. Despite its simplicity, the article was the most downloaded on the website for a long time. Maybe that tells us something about the state of reliability as cost constantly gets battled down.
A)- Rating equal 150% of the primary current (under no circumstances to be more than 300% - this is exceptional if the adopted secondary fuse rating at LV not exceeding 125% of the secondary full load current).
B)- Compliance to particular conditions related to protection of secondary side.
No matter what level of voltage you are dealing with, the ground wall insulation will be heavier than the conductor insulation. Potential to the ground wall is line voltage. Turn to turn voltage, especially in a medium or high voltage machine in minimal in comparison to the line voltage. The coils for medium and high voltage machines are made with the turns in a perfect stack unlike a random wound coil where it is very possible that the first turn of a coil can make contact with the last turn of a coil.. The turns of one coil can make contact with the turns of another coil.
By controlling the discharge of working fluid into the turbine, you control the Torque produced by the turbine and thereby the Power output. The minimum discharge required to keep the system at the required RPM is achieved by allowing enough discharge to overcome the system inertia so that the machine can rotate.
Before the proper spacing of ground rods can be determined, the site needs to be evaluated to determine the soil conductivity. Some of the software programs used for grounding system design resulted in infinite ground rods that still did not reach the maximum resistivity desired. Chemical electrodes are more costly but some site conditions warrant their use.
It is absolutely impossible for a utility to change the phase sequence. Why? Because the utility is connected to the local grid, the local grid to the regional grid, the regional grid to the national grid, and the national grid to the international grid. So, unless you don't change the phase sequence in the entire network you cannot change it locally.
The motor I need to stop is a 90W Single Phase Permanent Capacitor Induction motor, run straight from 230V AC mains. I'm not able to use a variable speed drive, separate DC injection braking unit or a DC electromagnetic brake. So I was considering DC dynamic braking, by applying DC voltage across the windings once mains power is removed.
The application was the addition of colours and flavours to a confectionary product and the required flow rates were very low. It was felt that a series of flow transmitters was an expensive and over-the-top solution, yet accuracies asked for and shifting conditions meant that simply setting the dosing pumps at a set rate was not adequate.
We know that the phase sequence is one of many conditions of the synchronization operation, and made in the beginning of construction. But if for any reason we need to check the phase sequence for two different sources of power. How to do that?
Driving the motor with sinusoidal voltages conveniently eliminates the issue of dv/dt related problems, voltage doubling effects and common mode currents flowing into the motor. The motor-side inverter of the variable frequency drive would have an LC-filter, and the capacitor voltage is a controlled sinusoid.
You can even get low cost variable frequency drives with low commutation resolution (8 bit and less) that WILL cause more audible noise in EITHER type motor irregardless of PWM frequency! The variables are infinite. The fact remains BLDC does not have to have different noise than an equivalent induction motor.
Current trend indicates that EPR cables are the preference over XLPE cables considering all the factors that are being evaluated. One very significant issue where EPR becomes more advantageous is on the issue of after installation "proof testing" of the cable. While EPR cables can take either a DC high pot testing procedure or AC High pot testing procedure, installation of XLPE cables do not guarantee / recommend a DC High pot testing on their cables.
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