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Fire Damp Transformers
rated 100 ÷ 500 kVA
General
The transformers belonging to this class comply to the requirements found in IEC 76, STAS 6877/1, 2 and to the mining norms in force. They are dry type, three phase movable transformer endowed with firedamp protection by explosion- proof encapsulation, equipment with connecting and signalling device, both on the HV and LV side.
Conditions of operation
in explosive atmosphere, in the coal mines and other industrial departments
max. ambient temperature +40° C; min. ambient temperature -15° C
air relative humidity 95 ± 3%; max. altitude 1000m
protection degree of the housing and terminal boxes IP-54
Construction parameters
The transformer is made of:
The transformer proper, with its components: the magnetic circuit, which is
made of carlyte insulated, cold rolled silicous steel sheet ; the windings,
which are made of glass-fibber and enamel insulated copper wire, impregnated
in electroinsulating varnish. The winding types used are: cylindrical on the LV side and
layer type on the HV side. The winding insulation is of glass-fiber fabric in layers.
Voltage control on the HV side is performed by changing the connections to the bushings.
The LV compartment affords achieving electrical diagram of the LV wiring within the explosion-proof
housing and has the following components:
USOL automatic breaker provided with maximal and overload
protection, with remote making and breaking tapping device, manually driven at remote making and breaking operations;
insulation resistance permanent and warning control device, disconnecting the secondary circuit when the insulation
resistance decreases below a certain value; measuring instruments : ammeter, voltmeter, current transformer;
terminal box with removable bushings affording connection of the supply outlets of the users, signalling-control;
The HV side duty is to energize and de-energize the transformer unit. Components and instruments: load special separating
switch for making and breaking the no load currents in the dry type transformer; it is manually operated, mechanically and electrically
interlocked by means of the LV circuit breaker; device to visually check voltage availability at the load separating
switch inlet terminals before penetrating into the HV compartment; mini-circuit breaker which automatically opens the dry type transformer
supply circuit, before penetrating into the HV compartment; terminal box with removable bushings affording to connect the supply and control signaling incoming wires.
The fire dump housing is made of steel sheet, having different thickness for the 3 chambers. The LV and HV compartment housings are provided
with doors ensuring safety, as per STAS 6877/2. The housing of transformer proper is provided with tubes for heat exchange/dissipation.
Outside, the housing is provided with: 4 wheels-undercarriage with 375 mm diameter, having the gauge required by the customer,
limit facility on the length, lifting lugs.
Technical characteristics:
The main equipment sorts of the group are presented in the following table:
Rating
(kVA) | Voltage
(kV) |
Uk
(%) | Po
(kW) |
Pk
(kW) | Connection group |
Overall Weight
(kg) | Overall Dimensions
(LxWxH)(mm) |
|---|
| 250 | 6/0.4 |
3.5 | 1.3 |
2.3 | Yy0 |
3925 | 2970x930x1595 |
| 400 | 6/0.4 |
4 | 1.5 |
3.1 | Yy0 |
4376 | 2970x930x1595 |
| 400 | 6/0.69 |
4 | 1.5 |
3.2 | Yy0 |
4250 | 2970x930x1600 |
| 500 | 6/0.69 |
3 | 2.75 |
2.6 | Yy0 |
4857 | 3125x930x1325 |
| 1. | Undercarriage |
| 2. | LV apparatus box |
| 3. | HV apparatus box |
| 4. | Cable inlet socket |
| 5. | Sight glass |
| 6. | Transformer lifting eyes |
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| 7. | Earthing terminal |
| 8. | LV terminal box |
| 9. | HV terminal box |
| 10. | Rating plate |
| 11. | Compartment doors lifting screw |
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