Some technical folks where I work say that a lighting study is not necessary for new lighting system installations because human perception is subjective. Other say that the study gives you basic information about the lighting levels.
I personally use AGI32 for every lighting study I do. It...
Hello:
We are in the process of upgrading our relaying system at our main substation. We are replacing all of our Westinghouse/ABB electromechanical relays with SEL relays + a SCADA system.
One modification that has caused concern is the replacement of the individual 15kV air circuit breaker...
Hello:
Short of doing an EMTP study is there any approximate method of determining the placement of surge arresters along a medium voltage aerial feeder?
Please consider the following:
1. Existing E/G system is a random access, parallel, three E/G switchgear.
2. A 3000AF drawout power breaker on E/G switchgear is presently serving a 480Vac, 1200A load using 4/phase 600MCM Al conductors. The linear distance is approx. 1000ft.
3. A new 3000A, 3...
Last year (May, 07) I brought to the attention of this fine forum the fact that I was the only electrical PE in the federal agency branch where I work. The situation is still the same. I asked our legal department about the ethical issues involved and I am still waiting for an answer. I did get...
Hello:
Can VFDs work with regular motors? What parameters should we observe?
At my agency opinions are divided on this issue: VFD rated versus non-VFD rated motors.
Thanks,
Jimmy Junior
Recently our engineering group purchased and started installling 4 firepump assemblies in our utilities plant. Each of these assemblies consists of a firepump controller, a pump and a 250HP motor. The decision to replace the older firepumps was made because the older pumps were installed in...
Hi:
I have a question about application engineering in the context of interior double-ended substations. To wit,
is it warranted to install TVSS protection on the secondary sides of double-ended substations between the transformer secondaries and the main secondary breakers (480Y V or 208Y...
Our principal administrative building is a 4 story office building served by six substations. These consist of 28 year old Westinghouse 12.47kV/480Y/120V and 12.47kV/208Y/120V double-ended substations. All of the transformers except for 3 are Westinghouse originals. All of the substations are...
At our federal agency we have at our Main Substation two 69/12.470kV, 15/20MVA, transformers feeding two walkin breaker lineups. Each lineup is fed from one transformer and the two lineups are connected by a NO tie ACB. Presently the transformers are protected by S&C Fuses. Soon S&C...
Hello:
I have been involved with Power System Analysis since 1976, before the advent of the PC. Back then we used main frames to perform short circuit calculations.
Where I work I am the only electrical engineer (and only EE with a PE) that has this kind of expertise and experience.
My...
Hello:
I am an electrical engineer trying to convince the folks in my group that when replacing a 1940s vintage 50hp pump motor with a modern energy efficient replacement, a lot more has to be done than just supplying the nameplate data. I think that proper engineering practice would dictate...
Hello:
I work for a Federal Agency as a Senior Electrical Engineer and have been a PE for 27 years. Our engineering department is multi-disciplined. All of our Branch Managers are PEs also. There are presently several electrical engineers working here, but I am the only PE. Our Agency does...
One of our domestic water distribution buildings has two fire pumps driven by Westinghouse 75hp 460/230Vac dating to the 1950s. The motor controllers are reduced voltage (resistor) types dating to the same era. These systems are working fine, except that we feel the motor controllers should be...
Our campus type facility is supplied from a 15kV dual lineup circuit breaker arrangement. Each lineup is fed from it own 20MVA transformer. The two lineups are tied through a NO circuit breaker. Each line up has 15kV, 1200A circuit breakers protected by the usual 50/51 overcurrent protection...
