Overview
The ZN28-12 series vacuum circuit breaker is a high-voltage indoor switchgear with a rated voltage of 12kV, three-phase AC 50Hz. This product complies with the GB1984-89 standard. The overall structure of this product is available in two forms: integrated installation of the switch body and operating mechanism, and separate installation of the switch body and operating mechanism. The integrated structure is the ZN28-12 basic type; the split structure is the ZN28A-12 type, suitable for fixed switchgear such as GG-1A(Z), XGN2A10(Z), etc.
This product can be equipped with CD17, CD10A DC electromagnetic operating mechanisms and CT17, CT19 spring energy storage operating mechanisms.
Main Technical Parameters
| Item | Unit | 20kA | 25kA | 31.5kA | 40kA |
| Rated voltage | kV | 12 | |||
| Rated current | A | 630 1000 1250 |
1250 1600 |
1250,1600 2000,2500 |
1600 2500 3150 |
| Rated short-circuit breaking current | kA | 20 | 25 | 31.5 | 40 |
| Rated short-circuit making current (peak) | kA | 50 | 63 | 80 | 100 |
| Rated peak withstand current | kA | 50 | 63 | 80 | 100 |
| 4S rated short-time withstand current | kA | 20 | 25 | 31.5 | 40 |
| Rated insulation level | kV | Power frequency withstand voltage (before and after rated breaking) 42 (gap 48) | |||
| Impulse withstand voltage (before and after rated breaking) 75 (gap 85) | |||||
| Rated operating sequence | Open-0.3s-Close-Open-180s-Close-Open | ||||
| Mechanical life | Operations | 10000 | |||
| Number of rated short-circuit breaking current operations | Operations | 30 | 30 | 30 | 20 |
| Rated closing voltage of operating mechanism | V | 110, 220 | 110, 220 | 220 | 220 |
| Rated closing current of operating mechanism | A | 71 | 71 | 71 | 128 |
| Rated opening voltage of operating mechanism | V | AC/DC 110, 220 | |||
| Rated opening current of operating mechanism | A | 30 1.5 | |||
| Contact gap | mm | 11±1 | |||
| Over-travel (contact spring compression length) | mm | 4±1 | |||
| Three-phase opening/closing asynchronism | ms | ≤2 | |||
| Contact closing bounce time | ms | ≤2 | |||
| Average opening speed (at 6mm just-opening height) | m/s | 1.2±0.3 | |||
| Average closing speed | m/s | ≤0.6±0.2 | |||
| Opening time | s | At maximum operating voltage ≤0.06 | |||
| At minimum operating voltage ≤0.08 | |||||
| Closing time | s | ≤0.1 | |||
| Main circuit resistance of each phase | μΩ | ≤50 | ≤50 | ≤50 | ≤30 |
| Allowable cumulative wear thickness of moving and static contacts | mm | 3 | |||
| Oil buffer cushioning stroke | mm | 10 | |||
