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Hi RRaghunath, We also have a busbar grounding switch. Besides, I am not getting your point. The cable side grounding switch is farther than the CB side switch-disconnector, so it would not be able to ground the busbar. Refer to attached image. Busbar is in the top and I am referring to the...

Hello, One client is requesting for the incomer of a MV gas insulated metal enclosed switchgear (arc resistant), to include two grounding switches: one in the incoming cable connection side and another one being the usual 3-position-disconnector/grounding switch that is located between the...

I know. This I explained already to Client, giving two options: either put tariff metering at Substation where we have both CT & PT of required accuracy; or pay to us to install PTs at Plant side. No success with any of the options. That is why I am asking for any experience with this PT...

It is for tariff metering. Client Contract clearly specified to measure current at one location and voltage at substation 5 km far. Although we have explained that this is nonsense, it is clearly specified in Contract and Client does not want to accept an addenda in contract for us to install...

Hello, I need to send the secondary 110Vac/sqrt(3)of a HV metering PT, to a remote location at around 5 km. I have found analogue to digital converters and signal transmission through fiber optic. However, for the remote end, I require also a 110Vac/sqrt(3) output, and I am only able to find...

Thank you waross. This is an industrial plant with a large genset that not only feeds motors with direct online starting but also UPS/DC system and other static loads. There is not a concern related to motor starting itself. It is a discussion with our engineering subcontractors that stick...

Hello, NEMA MG1 is specifying a maximum 5% frequency variation during normal operation and also during starting: "Medium motors shall start and accelerate to running speed a load which has a torque characteristic and an inertia value not exceeding that listed in 12.54 with the voltage and...

Hello, If my understanding is correct, a motor with an insulation class F with a temperature increase B has a 25ºC margin for operating continously without affecting its design life. If this is correct, one could use a motor purchased as F/B with no risk at F/F. My question is: if the rated...

Thank you 7anoter4, The question is that I never saw a busbar earthing switch in MV cabinets, only earthing switches in each of the circuits.

Dear all, For the design of 6.6kV cabinets, an engineering subcontractor is recommending to add a cabinet with an earthing switch so that in case that maintenance work has to be done in the cabinets, the busbars can be earthed before performing the Works. Cabinets are metalclad type and all...

Hello, It is a 220kV XLPE cable that will be laid in an existing rack. So they are 3 independent cables, one for each phase, that will be joined by cable cleats.

Good afternoon, A question has arisen among my workmates about piping racks foundations or supports sizing when carrying also for example ladder-type cable trays. Do the dynamic effects of short-circuits in cables need to be taken into account for sizing the supports? I usually only used...

Yes the power plant is new, it has a GT and ST. The GT has a GCB between the GTG and the corresponding GSUT, but the ST no, it is directly connected to its GSUT through an IPB, so synchronization will be done by closing a circuit-breaker that is at different voltage than the generator voltage...

Thank you both for your comments. A further question: once I have commissioned the transformer for the first time and checked that everything is ok following the procedures you explained, every time I open the circuit breaker, shall I have to repeat the commissioning procedure, or I can...

Hello, I have a ST Generator (15.75kV) connected directly to a GSU Transformer by IPBs, and then in the HV side of the GSU Transformer is a circuit-breaker (33 kV). As usually transformer manufacturers specify in their commissioning manuals that the transformer must be energized with no load...

Thank you. I saw aluminium motors indoors but not outdoors. I wanted to know which was the reason for this. Now it is clear to me.

Thansk slavag, So it is not for increased reliability reasons. I will check if the SC decrease is worth the extra cost of 1 UAT + IPB.

Hello, I have seen a tender for a power plant where the single-line diagram shows Generator + GCB + GSU Transformer + 2 UAT. The only way of feeding generator auxiliaries is through the UAT, as no station transformers of MV lines are available. The connection between Generator + GCB + GSU...

Hello, I would like to know which are the differences between cast iron and aluminium squirrel cage motors in terms of performance, environment withstand,... When should be a cast iron motor used and not an aluminium motor? Thanks.

Thank you all for all your replies. Marke, I will try that software. So the problem is how to calculate the weighting. I have the reactance of the supply so I would need the reactance of each VFD? Are there any technical papers that contain information about how to perform these calculations? I...