II need to calculate the impedance for 3-1/c #1/0 RW90 wires in steel conduit. This is the secondary of 240V single phase transformer. I have the values for 3-1/c wires and somebody told me that for 2 wire the impedance will double!
I can’t find any reference to this to back it up and he says...
Dear Friend,
I have a 45KVA pole mounted single phase transformer (7300V to 204/120V) which feeds two distribution panel, through 3C/1/0 cables in 2” conduit. I need to calculate short circuit current at the panel.
What I don’t have is the xfmr impedance and impedances on the wire.Could you...
IEEE 242 requires 15% margin between the main secondary curve characteristics and the primary fuse. I have seen several expressions in different books.
For example some books just consider .58% curve shift to the left for transformer damage curve and do not consider L-L faults. Like (SKM...
Utility has provided us with maximum and minimum 3P and L-G short circuit values. Which one of the values id recommended to be used for fuse, Circuit breaker Short circuit rating as well as short circuit study and coordination. This will determine which values to be used in SKM as utility data...
Dear Friends,
I am trying to figure out how hydro has calculated the L-L-G fault based on the following info. My answers do not match.
Based on IEEE 80.
L-L-G I0=E*X0/( X1*(X0+X2) + X2*X0) ( Page 96)
L-G I0=E/(X0+X1+X2)
X1=X2
Then I get
L-L I0=1763.98
L-G I0=2400.2
Hydro Info...
I have posted three different scenarios which a primary fuse can be chosen for a transformer. I know that the secondary CBK will need to protect the overload portion of the XFR and primary S&C fuse (SM5-Slow Speed) will take care of the fault through currents. However choosing a right fuse will...
Link below shows transformer protection with two different rating fuses. 40A and 50A
Transformer is 1500KVA 27.6KV to 600V. It seems that 40A fuse provides better protection however existing fuses are 50A. Secondary breaker is old H1-25 Federal pioneer breaker which I can not find any info on...
