How do you size a fusing transformer?
In lieu of transformer inrush data, the rule of thumb is to select a fuse size rated at 300% of the primary full-load current and round up to the next larger standard size.
Which fuse is used in transformers?
ABB WBP Transformer Fuses – Fuse Ratings & Dimensions
| Catalogue Number | Fuse Name | Rated Voltage U (kV) |
|---|---|---|
| 1YMB750747M2201 | WBP-6 | 7.2 |
| 1YMB751206M2201 | WBP-10 | 12 |
| 1YMB752405M3201 | WBP-20 | 24 |
| 1YMB753604M3201 | WBP-30 | 36 |
What size breaker do I need for a 75 kva transformer?
The rated current of the transformer can be used as the basis for a breaker. The rated current of a 3 phase, 75 kva transformer is 112 Amps, which is 25% of the rated current of a 125 Amp breaker.
How many amps can a 25 kva transformer handle?
Three Phase Transformer
| KVA | 208V | 480V |
|---|---|---|
| 20 | 56.6 | 24.1 |
| 25 | 69.5 | 30.1 |
| 30 | 83.4 | 36.1 |
| 37.5 | 104 | 45.2 |
Do transformers need a fuse?
All transformers are connected to the common secondary circuit through secondary fuses. The purpose of these fuses is to disconnect a faulty transformer from the secondary circuit. The size of the secondary fuse must be such that it will blow on a primary fault between its transformer and the associated primary fuse.
What is the function of J and P fuse?
Power fuse are generally accepted for protection on transformers in power stations. it provides an interruption on permanent faults.
What size breaker do I need for a 112.5 kVA transformer?
For a 112.5kVA transformer, 312A×1.25=390A, so use a 400A protection device.
How many amps does a 2kva transformer have?
You have a 2KVA (2000 VA) transformer and your primary voltage is 460VAC and your secondary voltage is 120VAC. Primary Amps = VA/VAC = 2000/460 = 4.35 amps. According to the chart above, 4.35 amps is in the range of the middle row, 2-8.99 amps, so the overcurrent protection should be 167% of the primary full load current. 4.35*167% = 7.26 amps.
What is the single phase voltage of a 75 kVA transformer?
This is the voltage supplied to the primary of the transformer. For example, if a 75 kVA transformer is connected between one-phase and neutral of a 13.2/22.9 kV three-phase system, the single-phase voltage is 13.2 kV. For an open Delta system where the voltage between phases is 22.9 kV, the single-phase voltage is 22.9 kV. Example for Chart 2
How big of a fuse do I need for overcurrent protection?
Primary Amps = VA/Primary VAC = 2000/460 = 4.35 amps. According to the chart above, 4.35 amps is in the range of the middle row, 2-8.99 amps, so the overcurrent protection should be 250% of the primary full load current. 4.35*250% = 10.88 amps. You can then round to the next fuse size which would be 15 Amps.
How much overcurrent protection do I need for my transformer?
You can then round to the next fuse size which would be 15 Amps. Secondary Amps = VA/Secondary VAC = 2000/120 = 16.67 amps. According to the chart above, 16.67 amps is in the range of the top row, 9 amps or more, so the overcurrent protection should be 125% of the primary full load current. 16.67*125% = 20.84 amps.