Question - Do I need to do anything special before applying power to electric motors that have not run since 1985?
I am restoring my father's John Deere Electric 90 electric riding lawn mower which was built in 1972 and has been parked in a storage shed a LONG time. It ran up to that time, but...
According to our arc flash study, we have a maximum of 47,000 A available 3-phase fault current coming into a 600 V cabinet via some really big copper buswork and wires. It connects to a main circuit breaker which is rated at 50,000 A. However, there are also three 4 AWG wires that tap off the...
Question - Is it normal for a Pad-Mount Transformer to have doors blow open when there is an internal arc flash?
Background
+ Equipment = 1.85 MVA transformer at 34.5 KV at a wind farm
+ Initial Electrical Failures - Elbow failure or Bushing failure
+ Typical Fault current 6-20 KA
+ Door...
Hello,
We are receiving a new substation at a wind farm equipped with capacitor banks. At a previous job, they used Joslyn zero voltage switches to engage the cap banks and during final testing a digital O-scope was used to confirm the timing was correct. 2 of the 6 switches had to be...
We are building a 34.5 KV collection system for a windfarm, and almost all the 3-phase cable is configured in trefoil. Occasionally, the installers make a mistake and in the middle of a circuit, one cable will jump through the other two. For example, you might have 1000' where the orientation...
I need a transformer expert...
Recently, during commissioning of a new 230 MVA 345-34.5 KV transformer we came upon an interesting problem. The LTC controller (Beckwith) was wired to monitor the low-side voltage and thus regulate it to a pre-set value, even though the LTC is built on the...
Hello,
We are building a wind farm with a 34.5 KV collection system. The contract calls for hi-pot testing prior to energization of all circuits. In addition to the hi-pot, the customer has recently decided to have the entire collection system tested by a reputable firm using Partial...
I'm hoping there's a cross-bonding expert out there...
We have a 34.5 kV underground circuit 9600' long. Our EPC is transposing the cables and cross-bonding the neutrals every 1600' (6 total sections), except at the mid-point, they neither transpose or crossbond (a straight-thru splice)...
I posted earlier this week about sheath testing on a 34.5 kV collection system and with the information I got here coupled with some information from the cable supplier, I now know why our EPC is failing these tests. Basically, (1) they were testing the sheath at too high of a voltage level (10...
Background: I'm working w/ a 34.5 KV 3-phase collection system consisting of multiple circuits each containing 12-13 2 MW turbines. The cable varies from 3/0 at the ends of circuits to 1250 kcmil at the substation, and it is direct buried in a sand bedding material.
Problem: Before the...
I'm a degreed EE, but my background is electronics and I could use some help.
BACKGROUND: I'm working at a wind farm site w/ a 34.5 KV collection system. The individual circuits feed into a 34.5 - 345 KV substation. The circuits are typically between 25,000 and 50,000 feet in length, and...
