Thank-you all for the information. The 6.1% is from the name plate but as mentioned I plan to use the higher value provided by the utility. Thank-you again
Good morning. I have a 2.5mw, 12.5kv/480-277v transformer with a %Z of 6.10. My understanding is the that maximum available fault on the secondary would be The transformers full load current divided by %z (Ifla/%z). The utility has provided a secondary symmetrical fault current of 56398amps...
So a bonding jumper needs to be installed from the MCC ground bar to the transformer neutral? I think I am getting lost in the terminology since the MCC is identified as a solidly grounded neutral I assume it needs a solidly grounded neutral run from MCC to transformer neutral.
Thank-you for the response. If there is no neutral bar where/how does the neutral get bonded to the MCC? Simply attach neutral to MCC ground bar? Also, does that also mean no grounding electrode conductor from MCC ground bar to ground rod at MCC? Thank-you for your knowledge.
Good Morning. The client has a Rockwell Automation Centerline 2100 series 480v/2000A MCC that is labeled as a 3phase 3wire Solidly grounded neutral (honestly have never herd of 3p/3w/solid neutral ground). The MCC is being fed from a 480V/277 wye xmfr whose neutral point is grounded at the...
Thank-you all for the feed back as it is greatly appreciated. The 1 hour does provide clarity as you have mentioned these fuse curves never go out that far and appear to be a straight line after the 5 minute mark. The clarify our situation over 600V and supervised with a fuse rated at 250%...
Thank-you both for the feedback. Yes I will be going by manufactures recommendation. What I still do not understand is that I could specify a 100E fuse for my 65A FLA transformer. The 162A current (250% NEC requirement) never hits the fuse curve of a 100E fuse which fuse blows in 5 minutes...
Hello. I am trying to size the primary fuse for 3.75mva-33kv/480v transformer. The NEC allows primary only protection at 250% for supervised installations which is my situation. My FLA is 65amps. When looking into fuse vendor data (ie., S&C, cutler hammer, little fuse, etc...) many list a...
Update. Ultimately ended up shaving the impeller by 7/8". Now system is working within acceptable limits even with the reduce flow and head. And yes while they are calling it 6 oil, it is various grades with various viscosity's. So have to point to this along with probably some poor...
Thanks again for all of the feedback. At the moment, will be replacing the spare siemens motor just to rule out if is a motor issue. If all motor and/or any electrical issue are ruled out then will have to conclude that the new product and piping configuration are such that more HP is...
Thank-you for the feed back. Yes agreed on the gate valve as it was not the intent to use it as a throttling device and are looking into an orifice plate. The pump curve was obtained from the vendor for 6oil and the previous application was 6 oil. Since different installation suspected that...
Thank-you all for the feedback and am investigating all suggestions. I will be looking at a spare siemens (RGZZVILESD) motor to see it it has the standard 6 leads that we can wire "Inside the Delta". This type of installation recommends a shunt trip on the Main CB. Does anyone know if the...
Thank-you. This is the wiring diagram I obtained from the factoryhttps://files.engineering.com/getfile.aspx?folder=c9aaf6d7-130c-4d2c-94b4-720f2cfed22a&file=150hp_reliance.jpg
I dont know what the current was uncoupled as we received the call from the electrician who stated that it ran fine uncoupled but drew high current when coupled and flowing product. We have a gate valve on the discharge and when first started and up to run speed the motor drew about 260amps...
