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I am not 100% sure I am clear, but I think you are asking if space heaters are required? Space heaters are more important for keeping equipment dry than they are for temperature. With such high humidity, if these motors are outside I would recommend it. However, I am not a manufacturer. If my...

tinfoil, My task is to size the equipment for the 'upstream utilitiy', or what I call off-site power. This is for a resort where there will other large loads besides homes, of which we'll have around 430 units or various sizes. There will also be a resort hotel and some other amenities. I...

Thanks, Saladhawks. This was helpful, although most of the homes in the development are off the chart. This is very difficult to define when one doesn't have access to customer loading data. jghrist, you are correct, these homes will be quite large, at least by middle-class standards, at 7,500...

I have been doing quite a bit of research looking for an applicable source to determine good values for coincident/non-coincident peak residential load values for sizing of a future distribution feeder. I know that many utilities use different assumed values for future residential customers, but...

Yes, I believe ASPEN will model it as a synchronous machine. The short term values I am OK with, but I am concerned about the longer period faults becuase I had heard that some of the new interconnection agreements were requiring a minimum of 1 s connection during fault conditions (in our area...

As I understand it, the DFIG is a kind of "partial syncronous" machine, in that the rotor circuit is boosted by the electronics but not to full synchronouse speed. I would think that if you pretend it is truly synchronous, this would be conservative, as a true synchronous machine would...

I am coming up on several interconnection studies for a transmission client. The Client's system uses ASPEN OneLiner, and most of the connections will be wind farms. I have a few ideas on how to model the wind turbines, but given that ASPEN is a very simplistic model, I am concerned about...

Johnarcher-Yes- I would expect to see a larger number of VARS consumed during motor starting, but a 1.5MW motor couldn't draw 8000Mvar, even if it were to effectively become a dead short that was 100% reactive- the MVAR requirements are around 5000 times the motor rated power draw. Even a dead...

You mentioned "At the instant of motor start"- if this is not a motor starting analysis (i.e. a transient analysis) then, is your motor modeled at locked rotor in a steady state load flow or did you mean 'after the motor has accelerated'? How is a 1.5MW motor, even at locked rotor, pulling 8596...

Hey folks, I don't know how many read Electricity Today, but they hvae an interesting article in Issue 6- EleQuant has developed a new Power Flow/Real time system called Agora that uses a new, NON-ITERATIVE power flow algorithm, which supposedly beats Newton-Raphson hands down. Unfortunately...

Perhaps I took the question "how I can control fluid in a pipe" in a more mathematical way (assuming he had already chosen a device), and thought the question dealt with control theory, rather than control mechanics. I certainly wasn't suggesting that he do all those things (thus the point that...

Cryopumps, The difficulty of this task depends on a few things. First, how accurate and/or stringent your control requirements are. For example, how accurate and how precise (defined differently) must the flow velocity control be, and/or the shut off velocity. Also, if you are comfortable...

Let me break down what is going on here without getting into the physics too much. The 'rule' you are speaking of above is that induction motors can be approximated as constant kVA on the power system. However, this rule, as you are discovering, is just that-an approximation. The relationship...

Deansharafi-FYI-Synchronous motor contribution also depends on the type of stator excitation, and can often be much worse than an induction motor, particularly in cases where the excitation is supplied by a seperate battery system, and thus excitation remains during the fault.

I suggest reading NEMA MG-1 for the definitions of these ratings. Also, there should be similar definitions for other types of wound equipment (in another standard).

Tulum, We had this exact situation at our plant. Here is what the engineer was saying: The mechanical load for the pump (there is no doubt this is a pump motor) has been calculated under "run-out conditions", which (I am no mechanical engineer) is basically comparable to a situation where...

As far as whether or not we would ever get comsumers, such as typical homes, to be powered from DC, I think this is highly unlikely. Everything is too standardized towards AC, and with so many independant companies building products for an AC powered home, it seems an insurmountable task to get...

I would think that a reactor in the input side would degrade the peformance of the VFD. Someone correct me if I am wrong, but the current demand of a VFD changes quickly (i.e. most harmonics on the input are harmonic currents) while the output is more likely to have harmonic voltages. Thus a...

Hey folks, I am working on a project at a substation that has some really old equipment in it. It appears that they are using a Quindar Quadraphase freqency shift keying PLC on one of their lines. I have done extensive web searching and have not been able to obtain a manual for this device...

Since the arcing fault is the only condition under which you will see phase to phase faults at or below your normal operating current (yes?), there are a couple of things you could do. First, some breaker manufacturers are producing breakers with arc-fault protection (optical). These devices...