milwaukeebob
Electrical
- Jun 21, 2004
- 42
Hello,
I was recently brought into a project that involves installing a new piece of electrical equipment into an existing substation. The new equipment (a harmonic filter bank) is being installed on the 24.9kV of the substation. The substation is located at ~7150 feet above sea-level and according to the existing drawings has a BIL rating of 150kV at that elevation (actually it's probably a little higher than that but the design and installation documents indicate minimum 150kV BIL).
Although the new equipment has not been built yet, I've been informed by the OEM that their system is 38kV Class with a 150kV BIL but this rating is at an elevation of <1000m (<3280'). The derated BIL at 7150' feet is approximately 132kV for the new equipment. This is the focus of my concern. Please note my decades of experience up to this point has been at elevations <<1000m (<3280') so I've never had to worry about derates in this regard.
The new equipment will have surge arresters rated 27kV, 22kV MCOV (GE# 9L11XPM027S) at the line input to the gear AND there will be another set of same rating arrestors outside the gear on the exposed 24.9kV line disconnect feeding the equipment. Note the existing xfmr feeding the system is solidly grounded.
My question is this - will these arresters provide adequate protection for the new equipment which has a derated BIL of 132kV? Regardless of the presence of arresters, I'm used to matching the new equipment BIL level to the requirements of the existing system.
Thanks in advance for any feedback and guidance on my concerns.
I was recently brought into a project that involves installing a new piece of electrical equipment into an existing substation. The new equipment (a harmonic filter bank) is being installed on the 24.9kV of the substation. The substation is located at ~7150 feet above sea-level and according to the existing drawings has a BIL rating of 150kV at that elevation (actually it's probably a little higher than that but the design and installation documents indicate minimum 150kV BIL).
Although the new equipment has not been built yet, I've been informed by the OEM that their system is 38kV Class with a 150kV BIL but this rating is at an elevation of <1000m (<3280'). The derated BIL at 7150' feet is approximately 132kV for the new equipment. This is the focus of my concern. Please note my decades of experience up to this point has been at elevations <<1000m (<3280') so I've never had to worry about derates in this regard.
The new equipment will have surge arresters rated 27kV, 22kV MCOV (GE# 9L11XPM027S) at the line input to the gear AND there will be another set of same rating arrestors outside the gear on the exposed 24.9kV line disconnect feeding the equipment. Note the existing xfmr feeding the system is solidly grounded.
My question is this - will these arresters provide adequate protection for the new equipment which has a derated BIL of 132kV? Regardless of the presence of arresters, I'm used to matching the new equipment BIL level to the requirements of the existing system.
Thanks in advance for any feedback and guidance on my concerns.
