13  EP 3 800 012 A1 14  36 V or 48 V, respectively, of the power tool (1). curing the plug 52 in the socket 52. [0047] Further,the powersupply unit40 may comprise a second electric socket 57 for releasably attaching the second cable41 to the power supply unit 40 (see Fig. 8). The second cable 41 is the power cable connecting the power supply unit 40 to the mains power supply. One end of the cable has the conventional plug 5a for con- necting the cable 41 to a socket of the mains power sup- ply. The opposite end ofthe second cable 41 is provided with another plug 58 adapted for connection to the sec- ond socket 57 of the power supply unit 40. As shown in Fig. 8, the second socket57 may beembodied as a con- ventional 3-pole AC current input module. In that case, the second cable 41 could be aconventionalpowercable comprising a mains power supply plug 5a on one end and the 3-pole AC current plug 58 for connection to the 3-pole AC current input module 57 on the other end. 15 10 5 20 25 30 35 the powertool(1) comprises an adapter element (4) having an adapter housing (15) at least part (8) of which corresponding to the form and design of the recess(7)and adaptedtobe inserted intothe recess (7) after removal of the battery pack (6), in order to allow electric connection of the adapter element (4) withthe powertool(1),the adapterelement(4)being connected to an external power supply unit (40) by meansofa firstelectric cable (5)and the power sup- ply unit(40)being connectable toan electronic mains power supply by means of a second electric cable (41), the power supply unit (40) comprising an elec- tric transformer (42) for transforming the electric en- ergy from the mains power supply into electric ener- gy corresponding to the electric energy supplied by the battery pack (6), in order to allow operation of the power tool (1) by means of electric energy orig- inating from the mains power supply and tra formed by the power supply unit (40). 40 45 50 Claims characterized in that 8 55 2. Power tool (1) according to claim 1, wherein the electric transformer (42) of the external power supply unit (40) is adapted to transform a voltage of 230 V or 110 V, respectively, of the mains power supply into an operating voltage of 12 V, 18 V, 24 V, 9. Power tool (1) according to one of the preceding claims, wherein the power supply unit (40) is adapted to comply with the ATEX 95 equipment directive 94/9/EC. 8. Power tool (1) according to one of the preceding claims, wherein at least that part (10) of the adapter housing (15) which is not inserted into the recess (7) upon com- plete insertion of the part (8) of the adapter element (4) to be inserted into the recess (7) and still visible from outside has the same design as that part (11) of the battery pack (6) which is not inserted into the recess (7) upon complete insertion of the part (9) of thebattery pack (6)tobe inserted into the recess(7) and still visible from outside. 7. Power tool (1) according to claim 5 or 6, wherein the attachment members (21, 49) comprise at least one spring-loaded hookelement(21)attached to one of the tool housing (2) and the adapter housing (15) and at least one corresponding recess or opening (49)attached to the other one of the tool housing (2) and the adapter housing (15), for receiving the hook element (21) upon complete insertion of the part (8) of the adapter element (4) to be inserted into the recess (7). 6. Power tool (1) according to claim 5, wherein theattachmentmembers (21,49)are adapted to au- tomatically enter into mutual engagement with each other upon complete insertion of the part (8) of the adapterelement(4)tobe insertedintothe recess (7). 1. Electricallydriven hand-guided powertool(1),in par- ticulara polisherora sander,comprising a toolhous- ing (2) with a recess (7) for receiving at least a part (9) of a battery pack (6), the design of the recess (7) corresponding to the part (9) of the battery pack (6) inserted therein,inorderto allow insertion ofthe part (9) of the battery pack (6) into the recess (7) and electric connection of the battery pack (6) with the power tool (1) and operation of the power tool (1) by meansofelectricenergy originating from the battery pack (6), 5. Power tool (1) according to one of the preceding claims, wherein thetoolhousing (2)and the adapterhousing(15)are provided with corresponding attachment members (21, 49) adapted to enter into mutual engagement with each other upon complete insertion of the part (8) of the adapter element (4) to be inserted into the recess (7)and toprovide fora releasableattachment of the adapter element (4) to the tool housing (2). 4. Power tool (1) according to one of the preceding claims, wherein the power supply unit (40) comprises an electronic filter element (47) for reducing interferences and suppressing electronic disturbances. 3. Power tool (1) according to claim 1 or 2, wherein the power supply unit (40) comprises a rectifier (46) for transforming an alternating voltage of the mains power supply into a direct voltage for the power tool (1).