I'm sizing the underground cable in direct buried conduits with 2 x 8 arrangement using ETAP software.The thermal resistivity (RHO) based on the geotechnical report indicates around 40 cm degC/Watts which is considered very low. The IEEE 835, and NEC basically list the soil RHO at 60, 90 , and...
Dear all,
Does anyone know why A and C Phase CT located on the line side of the main breaker (Polarity towards the top of the breaker) and the B Phase CT located on the load side of the main breaker (polarity towards the bottom of the breaker)?
I've never seen this application before. Please...
I'm working on a project where we need to install a 13.8kV-208Y/120V Transformer to feed non-rotating distribution loads. The Transformer is being fed from a remote source (located about 300 ft away) which has a breaker.
Do I need to provide a local disconnect switch on the primary side of the...
I have three-single phase transformer, each is rated at 250kVA, 34500-2404x7212/12490Y.
The name plate shows if the secondary side is connected in series the voltage is 7212V, 34.7Amps. If the secondary is connected in parallel the voltage is 2404V, 104 amps.
The impedance shows as 5.15% at...
Alehman,
The two 500 kVA Transformers are supplied by two separate 4.16 kV buses. The transformers feed the MCC through a three pole transfer switch (not a separate derived system).
Therefore, grounding the neutral at the upstream main disconnect are not required in accordance with NEC 250.20...
Dear Friends,
Thank you all for your responses. I should've clarified from the beginning that the term "Lighting MCC" is the MCC for Lighting Loads purposes.
Dear friends,
I have two 500 kVA Lighting transformers (4160V Delta - 480/277V Wye) coming through a three pole transfer switch to feed a 480V Lighting MCC. The transformer neutral is terminated at the MCC ground Bus.
Is it allowed to supply a 480-480/277V lighting transformer from the 480V...
I use 2kV (client's requirement) 3/C-500 kcmil w/gnd (4 cond/phase) which runs 916 ft to feed 800Amps Bus in Motor Control Center. The cables are oversized to avoid the excess voltage drop especially during the motor starting. These cables run through a 36" multi lay cable tray. I calculate the...
