Search results for query: *

Hi I am working for a DNO and we are doing a review of our commissioning requirements for some MV protection (Transformers, Reactors, and Feeders). Can anyone share the general testing requirements they see in their respective necks of the woods?

Hi All This seems like quite a basic question but what is the definition of 'measuring error' for a rogowski coil power metering system For example, systems are typically stated as having 1% rated accuracy for the rogowski coil and the measuring relay. Is this 1% of the measured value, or of...

Hi All We are designing a parallel hybrid vehicle which has an ICE engine driving a transmission and an electric motor coupled to the transmission output shaft. A direct torque coupling is used between the motor and transmission output shaft - the motor is basically driven via a belt drive...

We are working with a heating system which controls heat delivered to resistive elements by chopping out whole cycles of the AC voltage waveform. I.e. the SCRs conduct for one cycle, then stay off for 3 cycles, and then conduct for one cycle, would represent 25% heating power. It has got me...

Hi All, I need to source a 600A 5% line reactor for notching and harmonic mitigation of a 400V 550A three phase AC controller. I am in Australia, and availability of such things is very difficult. 5% line reactors are not stocked at all, and 3% reactors are stocked but only in sizes below...

Hi All We have a SCR/Thyristor heating system with a configuration shown in the attachment. The device is a phase angle controlled resistive Silicon Carbide heating controller We are seeing possible signs of line notching being caused by the controller - is this possible? I thought that line...

Hi All Was sure I would find this in the search, but no luck. Have an application where we have a 30kW motor with a 45kW vector drive. The motor is a fan which is controlling flow rate and requires good accuracy at very low shaft power (Its duty points are from 20kW to 3kW shaft power). I'm...

Hi All, I am trying to do an ad-lib dissemination of the functionality of devices like the Bender ISOMETER isoPV which are intended to perform insulation resistance measurement for energised electrical systems (i.e. PV plants). I do not fully understand the theory of operation, but what I do...

Hi all, hope you're well. I have been tasked with determining the cause for low insulation resistance in a utility scale PV system (2.5MW per inverter, 255x10kW strings per inverter, tens of inverters, and ~1000VDC operating voltage). The inverters are transformerless and the PV field operates...

Hi All, hope you’re all well! I am working on a customer site with lots of behind the meter generation. Power is from the supply authority with 2-off transformers, each feeding a separate main switchboard and sub boards. The supply authority requires us to limit the total export real power in...

Hi all, For a typical turbine generator in the MWs range , i.e. a Mercury 50, what work is theoretically required for it to provide synchronous condensing capability while it is not generating. I am not talking about decoupling the generator from the turbine, I am more talking about the...

Hi All Interested in knowing what work is required, in principle, to convert a generator to a synchronous condenser. I could write alot of possibilities out here that I have been thinking about but it is probably going to muddle the discussion - I will let you much more knowledgeable engineers...

Hi All, Can anyone explain to me: 1) What are 'PLC initialisation values", 2) What are 'Local initialisation values', and 3) Why I am getting a warning in unity pro 'the initialisation values in the PLC are different from those of the local application (see link below)...

Hey All, As some of you may be aware one cannot have too much inductance present in a dynamic brake (whether it's in the brake itself or the connecting cables). I am trying to confirm my understanding of the reason behind this. My understanding is that too much inductance causes overvoltages...

Hey All I am trying to understand the requirements for earthing of a 11kV/400V transformer which is installed on a jetty. The transformer is probably 1km from the shore and is fed from an 11kV switchboard located onshore. The transformer LV and HV earths are bonded together and are bonded to...

Hey All Regarding suppression of inductive voltage spikes for PLC outputs, I am after some practical guide for making the following decisions: 1) If the output does not have any suppression provided, what is the disadvantage of providing suppression at the PLC output terminals versus at the...

Hi All Here in Australia we commonly use 'V-90' PVC (thermoplastic) insulated and PVC sheathed power cable for cabling to final equipment, i.e. 3 phase motors, and for cabling to small distribution boards. This cable has a 'maximum operating temperature of 90 degrees" The standards here tell...

Hi All When it comes to first principles, a cable shield is intended to carry noise currents away from places they shouldn't be, and allow them to return to their source. Would you agree with this? In principal then, is it correct that a shield should be connected to the return terminal of the...

Hi All, We have a classic thermocouple issue as follows: 1) 10-off K-type 0-1100 deg C thermocouples 500m long connected to... 2) Non-isolated thermocouple converter with... 3) 4-20mA output from converter to a DCS/PLC. 4) The thermocouples are ungrounded, metal sheathed with a lead to lead...

Has anyone ever connected a HART-only device (i.e. without 4-20mA) onto a HART AI module?