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Hi all, Not sure that anybody experienced subsea umbilical cable ground fault problem? It is 1 phase LV cable (service Vmax 600Vac) and monitored with Bender IRDH375 and relay said low insulation value (600kOhm for trip setting). From theory with ungrounded system, it should be able to power up...

I've tried to find the safety starting time limit for a small DC motor and got some idea about the motor thermal time constant. Not sure is it appicable during starting period or not as the cooling is normally low. If it is yes, then the final heating = ( I start/I rate)^2 * (1-e^(t start/ time...

I would like to ask the way to connect ABB relay for configuraiton. I've tried with CAP505 and front connection port with optical link (1MK9500001-2) but the software show the problem with communication so I'm not sure the possibility for this problem. details: ABB REM543 CG212AAAA ,sw version...

I've run ETAP program for isolated power system. The system consists of 3x6.5MW turbogenerator (10A NGR) supply 6.6kV motors and 2x 6.6/.4kV 3MVA DYN11 transformer (solid earth). The calculation result surprise me and I would ask why this happen? In which case that LL and LLG can go over 3...

Hi all, I have a question of installation of CT link to differential protection relay, please see attached file. The problem is secondary CT connection was connect to ground oppose to generator terminal on both side which normal scheme will connect to ground on generator terminal side. (it...

I'm trying to looking for old voltage relay characteristic (curve) :Mitsubishi type CP-D ,CV2 and CV5 . Anyone can help on this. Thank you for your kindness.

Hello All, I'm trying to find transformer mothball ( keep in place ,not use for a few months) procedure, Could anyone suggest me the standard or procedure about that? My application is distribution transformer 1600kVA- 22kV/400V. Thanks for every suggestion. PAP

Hello all, I have a problem of Harmonic in the system but the harmonic monitoring is still in process, however , my concern is the dry type transformer that supply the load have some partial discharge trace. Could anyone may suggest how harmonic can accelerate the partial discharge process in...

All I have some questions about the temperature rise test for dry type transformer according to IEC 60076. What 're the meanings for this test, Can the test result infer to the operating temperature for transformer? ==================================== The method of standard is test by...

Hi all I 'd like to ask the implied meaning of operating cycle "O-t-CO-t-CO" with t range from 0.3s to 3 min , how the difference for varying of the interval time (fast cycle/slow cycle). Thanks all for your help.. PAP

Hi all I have a question about the under voltage protection for the main incoming of industrial plant. Its main incoming has only one feeder @ 22kV and connect to step down transformer (to 400V). Some problems were come from under voltage relay and undervoltage release coil in the main circuit...

Hello all Have anyone ever seen the DC output voltage(Line-Ground) of an 3 phase inverter when we supply with 380Vac(L-L),but don't send any starting command and speed reference is still 0 HZ? I 've measure this DC output voltage for all 3 phase,and it show 230Vdc(L-G) and 0 Vdc(L-L) ,but no...

Dear all Anyone please help me about the problem of a lot of spraking at commutator - carbon brush of a large DC motor. - Can I use abrasive material to resurface commutator? What material that I can use? - I found some dull surface on commuatator occur consecutively but not all of commutators...

Anyone please suggest about the technical reference and concept of activated carbon plant design ,both activated by steam and chemical. Thanks PAP

Dear all I'd like to ask for some meaning of this statement,what does it mean? " ... permissible starting duty with motor initially at ambient temperature 40C , 3 successive start are permissible.After which motor should be allowed to cool by standing idle for 1 hour or running for 1/2...

Dear sir I have interesting question about the protection of equipment (ie pump) that connect to the motor. In the past I've ever used undercurrent technic to protect the pump from low flow(loss suction) , but now I see some plant use power metering instead. Theorically ,power input to motor =...

Dear all Anyone please explain about the connection point of PT( to power system) for undervoltage realy in automatic transfer system that have 2incomer and 1 bustie. For my system relay 27 (undervoltage) and 27I (Instantaneous UV) are connected to PT that connect to the point of before...

Dear all Anyone can help me about the resource of the AFBMA standard and Bearing number comparison between AFBMA standard and Manufacturer (such as SKF,etc ). (I found it on name plate of motor and think that why this standard is generated to confused many people ? What's standard purpose? :(...

Dear sir I'd to discuss with anyone who experiences the failure of bearings of motor(2Z type) with no sign of vibration problem. What 's the possible root cause of this problem? REGARDS Prasit P.

Dear all Anyone please suggest me about the resource of the AFBMA standard and Bearing number comparison between AFBMA standard and Manufacturer (such as SKF). Thanks in advance for your kind. Prasit P.