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...
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...
