4.16GRDY/2.4KV-240/120V Station service transformer- 1

[Raj Adrika]

Could a grounded wye 1phase station service transformer (4.16GRDY/2.4KV-240/120V) be connected L-N on high impedance grounding (HRG- 160 ohm, 15amps)system? If not then could you please explain why? During a ground fault what would be the value of line TO N voltage across the Station service?

 

[waross]

It depends. It is a code issue.
In Canada it is allowed but there are provisions.
The neutral conductor must be insulated for line to line voltage from the 4.16kV supply transformer to the neutral of the station transformer.
The 2.4kV station transformer must have both bushings rated for system voltage ($.16kV)
The following applies:
Where line-to-neutral loads are served, provision shall be made to automatically de-energize the system on
the occurrence of
(a) a ground fault;
(b) a grounded neutral on the load side of the neutral grounding device; or
(c) a lack of continuity of the conductor connecting the neutral grounding device from the neutral point
through the neutral grounding device to the system grounding electrode.
While this is the law in Canada, it is a good idea in other places.
I would go with a 4.16kV transformer connected line to line.

Bill
--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[Raj Adrika]

Thanks a lot. Could you please let me know the Canadian code where its specified.

 

[Raj Adrika]

For the GRDY 1 PHASE Transformer there is only one bushing and H2 is coming from the winding without bushing

 

[davidbeach]

Single bushing transformers are not suitable for use on other than solidly grounded systems.

I’ll see your silver lining and raise you two black clouds. - Protection Operations

 

[waross]

C22.1-15 CANADIAN ELECTRICAL CODE, PART 1
Section 10 - Bonding and grounding.
Rule 10-106 AC systems
(1) Except as otherwise provided for in this Code, ac systems shall be grounded if
.......
(b) the system incorporates a neutral conductor.
......
Also.-
Installation of neutral grounding devices
10-1102 Use
10-1104 Neutral grounding devices


Bill
--------------------
Ohm's law
Not just a good idea;
It's the LAW!