Grounding in a HV substation

[livewire9]

Questions for my EE brethren:
1. In a high voltage substation is it standard practice to run a ground conductor the entire length of cable trench?
2. In a high voltage substation are potential transformers typically bonded to the ground grid?

 

[cuky2000]

Q1. In a high voltage substation is it standard practice to run a ground conductor the entire length of cable trench?
R1. Yes, it is convenient to run the ground conductor for additional protection. However, this is not a universal practice across the power industry. _{See additional info in the thread238-455845.}

Q2. In a high voltage substation are potential transformers typically bonded to the ground grid?
R2. Yes, usually the secondary and the chassis of the PT is grounded and bonded to the substation ground grid.

 

[dpc]

1. Yes
2. Yes

 

[bacon4life]

1. In my region typically a ground conductor is added to the trench, though I do not know of a specific standard that requires the practice.
2. The chassis of the PT is bonded to the substation grid. The PT secondary is grounded in EXACTLY one place. Often the PT secondary is grounded inside the control house rather than at the PT.

 

[cuky2000]

Hi Bacon4life,

Even though there are articles and independent researcher effort, I believe there is no explicit standard or official model to characterize the EMI for prediction on induced transient overvoltage in control and LV power cables.

Although many utilities use parallel-ground conductor in the trench, not all of them using this practice. For instance, It was suggested to a large host utility to include this mitigation strategy on an ongoing 230 kV, 80 kA switchyard project

Below is a partial literature survey on this subject. I hope this help.

 

[livewire9]

Thanks for the feedback, guys.