Transformer short circuit current.
- Thread starter lquadros
- Start date
- Status
- Location
- Mission Viejo, CA
- Occupation
- Professional Electrical Engineer
Re: Transformer short circuit current.
480V transformers do have an indirect through-fault rating - both thermal and high magnetic mechanical effects. But it has less to do with short-circuit availability on their primary than their own self-impedance.
IEEE Std 57.109 is a primary application guide for through faults. (If the fault occurs inside the transformer it is damaged already) It covers both the thermal and mechanical effects noted above. It also gives guidance to determine the expected number of through-faults a transformer may reasonably expect in its design lifetime.
480V transformers do have an indirect through-fault rating - both thermal and high magnetic mechanical effects. But it has less to do with short-circuit availability on their primary than their own self-impedance.
IEEE Std 57.109 is a primary application guide for through faults. (If the fault occurs inside the transformer it is damaged already) It covers both the thermal and mechanical effects noted above. It also gives guidance to determine the expected number of through-faults a transformer may reasonably expect in its design lifetime.
Re: Transformer short circuit current.
a transformer can only supply Fla/% Imp fault current. For example if your 480 transformer has a rating of 480 kVA and an impedance of 5% then the available fault current is 1000/.05= 20 kA. When a transformer sees large through faults they can be mechanically damaged. They also can get insulation damage based upon the heat created by the fault depending on duration of the fault. There are manufactures damage curves for transformers and while doing relay or fuse carnation that are used to protect the transformer.
a transformer can only supply Fla/% Imp fault current. For example if your 480 transformer has a rating of 480 kVA and an impedance of 5% then the available fault current is 1000/.05= 20 kA. When a transformer sees large through faults they can be mechanically damaged. They also can get insulation damage based upon the heat created by the fault depending on duration of the fault. There are manufactures damage curves for transformers and while doing relay or fuse carnation that are used to protect the transformer.
- Status