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The answer to both questions is an emphatic... yes! However, I strongly recommend that you investigate the viability of the single-phase source capability to run some 60-Hp load. I would also question the intermittent duty you cited. Additional information from you might elicit additional...

What is material? Power dissipation capacity? Exposure to high ambient or self-generated temperatures could affect the resistor's stability (not accuracy). Some materials will experience a permanent increase n resistance. Also, high humidity exposure will increase resistance, but this...

Responding to Peter Crowell's query (Tue, Aug 20, 10:22 am): At least for the last 50 years, motor starter panel vendors like GE, SqD, A-B, etc, provided schematic diagrams covering a host of pump-sequence circuits, They can easily be converted to ladder-logic. My question is an ethical...

How about a rain gauge! Regards, Phil Corso, PE (Boca Raton, FL)

Although quite late, this is my reply to the thread initiated in May 2001: Does the originator have an answer to the question asking how to determine if a motor is delta or wye connected? If not, and assuming that the original question concerned dual-voltage machines, then contact me...

In order to further broaden the knowledge-base of interested List members, attached is my reply to Tom's direct query: - - - - - Tom, Re E) Although the system is "ungrounded" the phases are coupled to "ground' via system capacitance. Thus, if the neutral of the auto-transformer were...

Attn: TR Gianni... Additional food for thought: In the spring of 2001, the List carried two topics that discussed unbalanced voltages associated with ungrounded or "floating" power systems. The end user you cited could be experiencing the same problem. The thread subjects were titled...

Replying to TR Gianni's questions (Thu, Aug 1, 10:21 am): A) Par 1. We agree. B) Par 2. What is meant by unbalanced source... Unbalanced voltages? Unbalanced kVA phase capacity of the power source transformer? C) Par 3. Your assertion that the algebraic sum of the line currents is...

Responding to H. Ozevin's comments (Thu, Jul 18): I agree, that, from your viewpoint, I provided more info than was requested. And, it is certainly true that your experience and mine are different. For example, I have seen VFD's with unbalanced motor currents and you haven't. My...

Responding to Suseka's query (Wed, Jul 17, 4:39pm) as well as several off-list queries concerning two-motor theory: First, I apologize for my failed attempt at humor. I just realized, that the pun on the word "negative" in my penultimate paragraph, probably went un-noticed because there was...

Further to my earlier response (Mon, Jul 15, 7:04pm): Add the following real-world "saving-grace" condition to the penultimate paragraph. "Third, few motors operate at or near rated ambient temperature." Regards, Phil Corso, PE (Boca Raton, FL)

Responding to stts' comments (Sat, Jul 13): Wow! Where did you get the word "shellac?" I haven't heard that term used since I did a job for a marine-shellac company, way back in the '50's! Regards, Phil Corso, PE (Boca Raton, FL)

Attn: P. S. Pandi: I want to apologize for providing instructions via text. My goal is to illustrate how just two power measurements can be used to determine power factor. This could refute the value of 0.98 that was obtained. (BTW, this method can also be used for unbalanced loads.)...

Responding to Bob Peterson's (Fri, Jul1, 11:26am) reply: Bob, you're mixing oranges and apples. The seal and barrier have different purposes. The seal's purpose is to: a) prevent the products of an internal explosion from passing into the Div 1 area; b) minimize the passage of potentially...

This is an area where I see/saw most errors. There are three problem scenario's: a) If the input-sensor circuit passes thru the Classified area, i.e., unclassified - classified - unclassified, then barriers are required at each interface. b) If the input-sensor circuit starts at an...

Responding to Matt's comments: Sorry, but I didn't interpret stts' query as a request for improving the cited formula. I thought he wanted proof that Vd is inversely proportional to T. Regards, Phil Corso, PE (Boca Raton, FL)

Responding to "Jim" Hebbard's query: First, a historical view. In the past, source/mains restrictions dictated the use of reduced starting-current technology. A users' option were, in general, limited to "country" preference. In Europe wye-delta was used often. Here, in the US wye-delta was...

Responding to Anonymous' reply (Tue,9 Jul, 2:05pm) to stts: Your advice is rather ominous. Actual conditions of load and ambient temperature were not presented. The values I produced were based on full-load and a 40 deg (C) ambient. The temp-rise over ambient is approx 3 to 4 deg (C) less...

My earlier response omitted an essential part of the derivation: Starting with, Id, current flow in forward direction is: Id = Io { exp [ (qVd) / (nkT) ], where: Io = Reverse saturation current. Vd = Potential across diode. q = Electron charge. k =...