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Responding to Rahmad's 08-Nov-09 (03:05) post... 1) Differential Protection. In this scheme two current measurements in the same phase, say I1 on one side of the protective zone, and I2 on the other, are compared. When a fault occurs within the machine, I1 will increase, while I2 decreases...

Parthipan... try ANSI/IEEE Std C2. Phil

Parthipan... thank you for keeping me informed of your findings... a common courtesy lacking in so many of the Forum's posters! I have a favor to ask: the difference between your measurement and my calculation is probably due to an error in my assumption regarding the cable's D/d ratio, where...

Blackstoneboy... for more info see: http://control.com/thread/1026222559 Regards, Phil Corso

Parthipan... the IR range, corrected for 300 mt length, is 40-46 Meg Ohms. Phil Corso

PARTHIPAN... Unfortunately, high-IR values are not an indication of high-dielectric strength, but, low-IR probably indicates low dielectric strength. If you are unable to obtain help from the cable manufacturer, then I suggest contacting other manufacturers. Finally, if all you require is...

Cdymk... following are the answers to your two questions: o LV voltage is usually more readily available. o Typically the 2-Watt meter method is used, but if the LV winding is wye-connected, then the 3-Watt meter method can be employed. Regards, Phil Corso

Serpil981... the PTs should not be disconnected. Only the NGR is disconnected for the acceleration period during which the the generator operates as a synchronous motor! Regards, Phil Corso

If you are sure of its age, then please answer the following: o What is the installation? In metallic or non-metallic conduit; in air or buried, nitrogen-cooled or oil-immersed? Regards, Phil Corso

Speedtronic, see: http://control.com/thread/1026242938 Phil Corso

Adiul, re: your comment regarding power measurement in an unbalanced system.. Contact me Off-List if you want info on how to do it with single-phase clamp-on meter! Regards, Phil

Kunal... typically, RTD's used to monitor motor temperature are embedded in the winding slot. Thus, they are not replaceable and a duplex arrangement increases monitoring reliability! Regards, Phil Corso

Adil... unless the second drive has comparable measurements, then I, like Roy confirm the motor is at fault. Phil Corso

Adil... The amperage test, while providing additional information, did not provide any more knowledge than was provided by AUF calculation. So, hopefully you are interested in learning more about failure-mode. If so, then bear with me regarding the following questions: o Is the motor still...

Adil... there are additional tests you can carry out. However, more data is required; please provide the motor's rated speed, power-factor, and efficiency if known! Regards, Phil Corso

Adil... there are additional tests you can carry out. However, more data is required; please provide the motor's rated speed, power-factor, and efficiency if known! Regards, Phil Corso

Cesar... contact me Off-List if your are unable to extract the info you need from the Control List Archives! Regards, Phil Corso (cepsicon[at]aol[dot]com)

Serp1981... Reur your question about open-delta xfmrs... the reason is economic, that is, only two transformers are required instead of three! Reur question about disconnecting the NGR... see: http://control.com/thread/1240942296! Regards, Phil Corso

Robert, give the guy a break... I believe you have confused water (plenty of that here in Florida) with snow (plenty of that in Michigan), A cubic-foot of water (at least here) weighs 64 lbs!

Correction to my 20-Oct-09 (12:18) post (my apologies to those uncomfortable w/equations): H) (Was G) Circulating current is proportional to the product GEN1xGEN2xSIN[(displacement Angle)/2)], but inversely proportional to the sum of impedances between the two sources, that is...