Search results for query: *

I am looking for a standard number (prefarable IEC, but reference to any other standard would also be helpful) regarding the numbering of panel-wires. M is for instance a motor circuit, C10 a protection CT circuit on the red phase, B a busbar CT circuit, J the DC control voltage, etc. Thank you...

jghrist: No motor contributions. See it as a transformer feeding a bus, with the incomer to the bus open. Thus, just the transformer energized. Now I understand that that the fault-current would be 3Io, but why are the software-calculated current so much higher than the hand-calculated...

Thanks for both of you. The intention of my hand-calculations is to ensure the software calculations are correct. Kind of a double-check or a check-up. Literature indicate: Ia1 = Ia2 = Iao = Ea / (Z1 +Z2+ Zo) Do I have to add the three together? Ia1 + Ia2 + Iao = Ifault And what will the...

I am doing a three phase and a single phase to ground fault calculation on the secondary side of a transformer. But the answers I obtain from my software-program and the answers from my hand-calculations (invinite bus) are not the same - somewhere I am doing something wrong. Trsf data: Rating...

If I may ask: Will there be any differences if a Wye-wye transformer is used, but the primary neutral is not grounded? Thanx

Thanks all! The motors are not on the same pulleys. (2 pulleys on one belt) There are fluid-couplings between the motors and the gearboxes. The problem is that one motor can't take a fully loaded belt away on its own. (Without any material on the belt there is no problem) With a long delay...

We have two motors on a conveyor belt (Each 50kW) How do you determine the time-delay between the start-up time of the two motors? (DOL-starters) I don't want to start both imediatelly (due to the high start-up current), but I also don't want the time-delay between the start-up of motor1 and...

Thanks for the replies. jb: The only nameplate data avaliable is the data in my first post. There is 4 different size motors (Slipring motors, same manufacturer) The only data again: Motor 1 Power: 500kW rpm: 1483rpm Stator V: 3300V Stator I: 115A Rotor V: 855V Rotor I...

I want some data on some old WRIM-motors we use in our plant, to check their settings. The manufacturer doesn't exist anymore, so I don't know where to obtain the data. Can I assume any values or is there any average value I can use for: 1. Safe hot stall time? 2. Permissible start attemps /...

Hi all Is there any way how you can determine the kneepoint of a protection CT with the nameplate values?(IEC ratings) To determine the kneepoint with a voltage source and a ammeter is no problem - I want to know if it is possible to find it mathematically. Thanks

Thanks again for all the replies Maybe my original question is a bit confusing - so let me try again 10P10 1000/1 CT's Earth fault current 8000A E/F relay setting on 10% (pick-up 100A) but relay is effective up to x20 plugsetting (effective up to 2000A - earth fault current is 8000A (x80 of...

dpc: Thanks for the reply! I have no problem with the time-interval between the relays. My problem is on which current to add the 0,4sec. In the example I've used when I started this thread (10% setting), the relay will be effective up to 2000A, but on higher currents it will not - I think...

I have a question re relay coordination on electromechanical IDMTL earthfault relays. Take a system with 10P10 1000/1 CT's. Relay is 2xOC and 1xEF. Take a earth fault setting of 10%, meaning that the relay will pick-up at 100A. Most relays claim to be effective up to x20 plugsetting, in this...

What is the time interval between a high-set (instantaneous) unit and IDMT-relay? I know time between relay-relay is 0.3 - 0.4 seconds, is it the same between high-set and relay or not? Thanks

Thanks for all the replies! Due to unforseen circuimstances,I haven't been able to reply to your responces. Marke: I'll give you a red star for your comments. jraef: You are right, this is a overland conveyor system (iron ore) jbartos: I am not sure what you asked, but like I said, there is...

On our conveyors we have slipringmotors. Some of the conveyors have just one motor, the longer belts have up to three motors. On all our motors we have vapourmatic starters, but with statormatic probes. (Each motorstater have three steps to bring the drive on speed) The motor sizes varies from...

We are using diesel-electric trucks in our mine. (open-pit) When the trucks take some inclines, they use overhead lines, or pantograph lines, to supply them with electricity. It is 1600V DC, and it is supplied through 1440kW 11kv/1200V 3ph transformers, and then rectified with a three phase...