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Hi, I intend to use stainless steel wire instead of copper as grounding conductor. I understand that copper is a far better conductor than steel. Is there any regulation which prohibit the use of stainless stell as earthing conductor? Thanks for any advice. Grundig

Hi, Help forum forum members ! We are having intermittent phase to phase fault on a distribution panel @ 590 V. We could see trace of arcing between the phases on the incoming circuit breaker feeding the common bus in the panel. The circuit breaker was replaced. Before energising, the...

Hi, I visited a site where they used a potential transformer to sense ground fault on their 22 kV / 400 V transformer. The PT is rated at 13 k V/ 110 V . This sound strange as the PT should have been sized at the rated line/line voltage of the transformer. Any comment ! Grundig

Hi, I have seen many installations where the star point of MV alternators are high impedance grounded. There are nothing uncommon with these practices and they are done almost all the times. What is uncommon is that when the alternator is not in service, the network works ungrounded. I just...

Hi, I`m looking for guidelines on how to measure the capacitive charging current on a 400 V 3500 kVA system.The intention is to limit the ground fault current close to the capacitive charging current. Thanks. Grundig

Hi, In the SDS of Sulphur dioxide gas, it is mentioned that the critical temperture of S02 gas is 175 deg C. We used to operate ou process regularly with SO2 gas well above 200 deg C.Basically, what does the critical temperature menas? Thanks for your respeonses. Grundig

Hi, First of all,please bear with me as I`m not a turbodynamic guy. I `m rather an electrical one. I will introduce the picture of the situation.I work in a dyeing factory located close to a power generation plant. We have a contract with the plant and the power plant supplies us with...

GHi, I did an infra red inspection on one 6,6 k V 3 cores XLPE Cable entering my 6,6 k V panel. There is nothing wrong on the terminal connections to the panel and nothing wrong either on the transformer terminals connection. The inspection is showing that part of the cable is heating as shown...

Hi, I just installed one 1500 A ACS800 drive. It`s running on DTC control mode and the motor is drawing excessive current at half nominal speed. Another drive of different make hardly drew 60 % nominal current at that particular speed. The ACS drive drew around nominal current at that speed. I...

Hi, I am actually designing one 11 k V distribution switchboard for a factory. The national grid feeds at 22 k V. There is one 10 MVA 22/11 k V Yd11 transformer, rather new and in very good condition,and the management is pushing to use this transformer. The 11 k V distribution will feed four...

Hi, We have on site one 4,0 MW 11 k V wound motor which has been operating well since installation two years ago.The insurance company is now pushing us to overhaul the motor for bearing and winding inspections.We have contacted the motor manufacturer and they said that this decison should be...

Hi , I am looking for the opinion of the gurus on this site concerning the sizing of the neutral bar relative to the phase one in a TT scheme installation. Grundig

Hi, My transformer, ONAN 3,0 MVA 11 k V/ 400 v , used to trip on earth fault protection. I have got a zero sequence CT wired to my relay with a setting of 0,1 A instantaneous.We had four trips in the last week. The transformer has been sucessfully megerred, PI > 5 , and di-electric test also...

Hi, I need your help. I have got a 1.0 k VA 230 V 50 Hz ups which is powered through a 400 V/ 230 V isolating transformer. The idea behind using the isolating transformer is to get rid of the supply neutral which had found in the past to be quite unstable.So long as the supply is solidly...

Hi, We are in the process of installating two 2,0 MW 6,6 k V electric motors mounted on the end of a common shaft to drive a stone crusher. The two motors are identical as far as full load slip is concerned.What are the issues other than mechanical-alignment, vibration..-that need to be...

Hi, I was approached recently by a safety professional on the need to install safety mats near all of my motor control centres particularly on the requirement of safety mats agains static electricity. There is no statutory safety requirement to install such locally.I need to motivate this...

Good day, I work in a food manufacturing company and we have our own generating plant 15 MW and twelve sub-stations supplying equal number of motor control centres @ 400 V 50 hZ. There are quite frequent interventions on the MCC by the electrical team. There is a demand from the electricians...

Hi, I need to protect a 3,0 MW 11 k V electric motor. The 11 k V supply comes from a nearby power station, where a 11 k V cable is run to my 11 k V distribution panel, and the maximum earth fault current is limited to one amp at the power station. The protection relay I am using is limited to a...

Good day to all, We are looking at the opportunity to purchase a second hand generator 6.0 MW 6,6 k V rated . However, our network is rated @ 5,5 k V. Basically,running the generator at 5,5 k V and obviously at the rated speed, the capacity of the generator will be limited by the ratio 6,6/5,5...

Hi, I need to size my current transformers to protect a 1 MW 6,6 k V wound motor. The protection current transformers available in an existing panel are rated 300/1 5P10 10 VA( 0.5 class of accuracy ).I reckon that the starting current for a wound motor is 2-2.5 the full load current that is...