COMPARISON DATA
Comparison Chart of 250VA power transformers using 3 different types of cores
| Feature | O-CORE | TOROIDAL | E-I CORE |
| Height | 1.375" (34.9 mm) | 2.2" (55.8 mm) | 4.7" (119.4 mm) |
| OD/Width | 4.5" (114.3 mm) | 4.5" (114.3 mm) | 3.9" (99.1 mm) |
| Depth | -- | -- | 4.3"(109.2 mm) |
| Volume | 22 cu.in.(361 cm3) | 35 cu.in.(574 cm3) | 78.8 cu.in.(1291 cm3) |
| Weight | 3.6 Lb(1.63 Kg) | 5 Lb (2.27 Kg) | 10 Lb (4.54 Kg) |
| Mounting Requirements | Single Bolt Through Center | Single Bolt Bolt Through Center | Bolts in Four Corners |
| Magnetizing Current | 16 mA | 18.3 mA | 160.0 mA |
| No-Load Losses | 1.7 W | 1.7 W | 20.5 W |
| Continuity of Magnetic Path | 100% parallel grain orientation | 100% parallel grain orientation | 50% of grain Perpendicular Causing higher Eddie Currents |
| Magnetic Properties of Core | Optimized prior to winding and remain Stable | Optimized prior to winding and remain Stable | Negatively impacted Properties Stable by clamping, welding or banding. |
| Coupling Factor | Maximized by evenly distributed winding on the core and close proximity to the actual core itself. | Maximized by evenly distributed winding on the core and close proximity to the actual core itself. | Limited by bobbin width and layers of windings. |
| Long-Term Reliability | In excess of 10 years | In excess of 10 years | Performance degradation over time from thermal cycling and vibration. |