Vault disconnect switch on Primary Subs
Vault disconnect switch on Primary Subs
(OP)
I have 34.5KV line to 4160V. On the primary side of the transformer there is a vault with a disconnect switch (3 phase). This is fed from an overcurrent protection device some distance away. There has been problems with the disconnect switch so Im looking into getting rid of it, and I was wondering if it is "legal"? Is there NEC code requiring the switch, and/or any other issues that might arise from getting rid of the switch.
Be Safe.
Be Safe.






RE: Vault disconnect switch on Primary Subs
But if this is owned by a utility, the NEC does not apply.
RE: Vault disconnect switch on Primary Subs
This XFMR is owned by our facility. Our overcurrent device is ~ 800 ft away and we can apply grounds there.
RE: Vault disconnect switch on Primary Subs
RE: Vault disconnect switch on Primary Subs
RE: Vault disconnect switch on Primary Subs
RE: Vault disconnect switch on Primary Subs
RE: Vault disconnect switch on Primary Subs
The insulation around the switch had moisture build up on it. This created a low resistance to ground resulting in some arcing and ultimately causing damage to the switch, insulation and vault. NOTE: we do have heaters inside the vault to avoid this problem but it seems they had some type of failure.
RE: Vault disconnect switch on Primary Subs
What kind of switch do you have in this facility?.
Did you check with the switch manufacturer for this application?
RE: Vault disconnect switch on Primary Subs
RE: Vault disconnect switch on Primary Subs
RE: Vault disconnect switch on Primary Subs
RE: Vault disconnect switch on Primary Subs
RE: Vault disconnect switch on Primary Subs
I agree with you and zogzog that it will be cheaper to service the switches rather than removing them. We our using a silicon to lube the mech., we do check switch operation periodically, and Im not sure how often the insulators have been cleaned. We will be changing to a more reliable heater and possibly putting a screw plug type heater into the side of the enclosure with a metal casing surrounding it thus allowing us to replace the heater element without de-energizing. I was interested in removing the disconnect switch because we will purchasing new Primary subs and will likely get rid of the disconnect switch being that it is "legal" to do so. However we still need to heat the vault to ensure no moisture build up on the primary side of the XFMR.
thanks.
RE: Vault disconnect switch on Primary Subs
RE: Vault disconnect switch on Primary Subs
Thanks for the info. on the IR scans I will look into putting those on the vault doors of the new subs for preventive maintenance.
RE: Vault disconnect switch on Primary Subs
RE: Vault disconnect switch on Primary Subs
Thanks and
Be Safe.