Silver Graphite
Materials
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|
| Type | Fine | Medium | Large |
|---|---|---|---|
| Graphite content in % | 3 – 4 – 5 | 3 – 4 | 3 |
| Grain size | 1 to 5 μm | 5 – 40 μm | 20 – 160 μm |
| Metalor' designation | F | M | G |
N.B. : in certain cases, a TGG (extra coarse) grain size might be needed, available on demand
Manufacturing processes
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| Technique | EXTRUSION | DIE COMPACTING | |
|---|---|---|---|
| C – Grain alignment* | PERPENDICULAR | PARALLEL | RANDOM |
| Metalor's designation | ET | ED | U |
| Contact surface | 10 to 200 mm² | 10 to 400 mm² | no limit |
| Contact thickness | 0.35 ≤ h | 0.40 ≤ h ≤ 1.5 | 0.50 ≤ h ≤ 2.5 |
| Available forms | Tip – Wire | Tip – Profile | Tip |
N.B. : in certain cases, tips obtained through die compacting are pressed a second time
* In relation to the contact surface
Physical characteristics
| Grain size | Fine | Medium | Large | ||||
|---|---|---|---|---|---|---|---|
| Graphite content in % | 3 | 4 | 5 | 3 | 4 | 3 | |
| Theorical density g/cm³ | 9.46 | 9.16 | 8.88 | 9.46 | 9.16 | 9.16 | |
| IACS conductibility Measured by eddy Current method % |
ET | 78 | 64 | 59 | 83.5 | 75.5 | 82.5 |
| ED | 88 | 80.5 | 78 | 87 | 81 | 90.5 | |
| U | 67 | 57 | 49.5 | 82 | 76 | 81.5 | |
| HV hardness | ET | 45 to 55 | 40 to 50 | 40 to 50 | 30 to 40 | 30 to 40 | 30 to 40 |
| ED | 35 to 45 | 35 to 50 | 25 to 35 | 33 to 40 | 30 to 40 | 30 to 40 | |
| U | 30 to 40 | 30 to 40 | 25 to 35 | 25 to 35 | 25 to 35 | 25 to 35 | |
Underlayer characteristics
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| Silver face | 1 FACE | 2 FACES | 0 FACE |
|---|---|---|---|
| Underlayer thickness e | 10 to 150 μm | 0 | |
| Underlayer with solder plating | yes | yes | no |
Other characteristics :
- The underlayer in the case of random structure my be fine silver, or there may be no underlayer at all.
- Solder material : any type which is adapted to the assembly
- Identification of the solderable face through marking to be defined in cooperation with the customer
Designation
Metalor's wide range of material necessitates an accurate description : structure, number of silver faces, grain size, graphite content.
- FET 1-5 : Tip with fine grain, perpendicular structure, 1 silver face, 5 % graphite
- MED1-3 : Tip with medium grain, parallel structure, 1 silver face, 3 % graphite
Electrical characteristics
Because of its properties, AgC is the ideal material for protection switchgears : high breaking capacity, low resistivity.
The properties of AgC depend upon the amount of graphite added, the manufacturing process and grain size.
Example, as a rough estimate, for a 5 000 A breaking test :
| Graphite content in % | 3 | 4 | 5 | |
|---|---|---|---|---|
| Erosion (mg) | FET | 31 | 45 | 62 |
| FED | 100 | 122 | 143 |
Applications
Switchgears
- Any protection swichgear requiring breaking capacity at 16 to 1 000 A rated current :
- Circuit Breaker for home
- Residual Current Circuit Breaker for home
- Industrial Circuit Breaker for industry
- Contactor Breaker for industry
- Any switchgear utilizing sliding contacts
- Any contactor incuring risks of micro-welding