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Hi All Type in "short Circuit Calculations" into the Google search engine, and you will find a lot of information on this topic. Below is information from one web site, I found, where you can purchase a book at a reasonable cost. I am not selling or promoting the book...

I obtained the UL number and looked it up on the UL web site. The Catalog number of the soft starter is listed on the UL web site, under the number given. All it tells you is that it is a Solid state motor controller.

I am looking for information on electrostatic oil cleaners, for use on a hydraulic oil system. We are having problems with the build up of varnish in the system. The hydraulic system is used on a steam turbin and operates at 1200 PSI. Can anyone point me to a good sourse of technical...

Hi, I am looking for information on electrostatic oil cleaners, for use on a hydraulic oil system. We are having problems with the build up of varnish in the system. The hydraulic system is used on a steam turbin and operates at 1200 PSI. Can anyone point me to a good sourse of...

Hi, Thanks for your response to my post. I have contacted the manufacture of the relay, GRUNER AG, and this was their reply. "As the relay is used as a bypass and is only carrying the voltage and current and does not switch it, there is no problem to use it for this application.&quot...

busbar, Sorry it makes you nauseated. But that's life in the industrial corporate world today. Just trying to get all of the ammo I can. There are more good projects than $$ to go around. Those that build the best case first, gets the prize!! Have a good day.

HI, Several folks on this forum, plus discussions with other electrical engineers, has convinced me of the need to install High Resistance Grounds (HRG) units on all of my 480 Volt and 2400 Volt ungrounded delta substations. I have been allow to purchase one unit, so far...

HI, I would like some opinions on this. A Mfg. rates a small single pole relay at 40A/250VAC. The applalication the relay is used in, the current the contact will normally see is vary low, on both make and break, maybe less that 1 amp. Its used to bypass a set of SCR's, which will be fully...

GGoss Thanks for the offer of help. I would perfer not to name the make and/or model of the soft start controler (SMC)that we are using. I am receiving help and support from two different manufactures of SMC's, including the manufacture of the one I am using, as well as from some power...

RJF, and d23 The ground alarm system is a home grown system but using all standard components. I do not have HRG on my 480 volt Delta unit subs, so I used a ground detector made by Erickson Electrical Equipment. The Erickson unit gives me a dry contact. I hooked up the Erickson to the...

RJF The SMC units do have a fault code. We are getting "Phase Loss/Loss of Load" and sometimes "Phase Imbalance". In talking the some of the design engineers from two companies who make SMC's, isolation transformers, or reactors in front of the SMC,s will not help. One...

tmahan I have a system in place that capatures, time stamps, and stores every ground event in a database, on all of my substations. I can look at the past history of ground activy on any substation. Every time I had an SMC drop off line, I had recorded ground activity on the substation...

jraef Both Allen Bradley, and Cutler Hammer have units with an internal bypass. The AB SMC-3 unit has an internal bypass. The Cutler Hammer models S751, and S801 both have an internal bypass.

dpc & Mark Thanks for the replies. You have been a big help. In my case, the SMC I am using has internal bypass contact around the SCRs. The SCRs are not being damaged, the SMC units just drop off line. The additional bypass contactor I plan to install will be used to get the SMC electronic...

busbar, Thanks. I have worked with ungrounded systems for over 30 years myself, in several different industrial plants. (23 years in this one) I purchased a copy of Beeman's book years ago, and it is well used.

busbar Thanks. I have read most of the post about ungrounded 480 volt systems. I have studied the subject in great detail and understand the issues with unground systems. I have ordered a high resistance grounding system to be installed on this unit sub. However, I have about 40 unit...

Hi, All I just read the 12 or so, different post about soft starters, and I have a different question reguarding the use of these devices. We have installed several SMC soft starters over the past six months. They are on a 25 HP motor, 480 volts 3 PH. The 480 volt power system is an...

Just found an interesting article that is related to this topic. It talks about, on high-resistance grounded systems, some engineers are selecting a 2kV cable where a nominal 600V cable could be used. They feel the extra insulation thickness handles voltage anomalies during fault conditions for...

From above thread... ....." unless you have a serious problem with insulation degredation due to damage, age and heat related failure, etc." True, On a 480 volt system, you should not have arcing, until you start having insulation problems. But where you do have an insulation...

Try this: All Resistor = 5 ohms find REQ Establish points A & B Establish paths V1, V2, & V3 V1 = I/3 R V2 = I/6 R V3 = I/3 R Vab = V1 + V2 + V3 = I REQ Vab = IR/3 + IR/6 + IR/3 = I REQ IR (1/3 + 1/6 + 1/3) = I REQ IR (2/6 + 1/6 + 2/6) = I REQ 5ohms (5/6) = REQ 25/6ohms = REQ 4.17ohms = REQ...