fig1 a shows a rotation direction recognition by way of the pressure h , i . e . of the pressure at the exit side of the pump . fig1 b shows the rotation direction recognition by way of the throughput q through the pump , and fig1 c shows the rotation direction recognition by way of the power p , i . e . the electrical power of the drive motor . for determining the correct rotation direction , the pump assembly is driven in both possible rotation directions , and at least one performance characteristic value , specifically for example the pressure h , the throughput q or the power p , is detected with each rotation direction by a rotation direction recognition module . subsequently , the difference between the performance characteristic values determined with both rotation directions is formed . i . e . in the case of fig1 a , the pressure difference δp between the pressure p cw in the first rotation direction , and the pressure p ccw in the second rotation direction is formed . accordingly , for the embodiment according to fig1 b , the difference δq between the throughputs q cw and q ccw of the two rotation directions and according to fig1 c the difference δp of the powers p cw and p ccw are determined . thus the following formulae arise : a region surrounding the origin is represented in a hatched manner in fig1 a - c . this characterises the region in which a reliable recognition of the correct rotation direction is not possible on account of too small differences between the performance characteristic values detected with both rotation directions . if the result δh , δq and δp lies in this region , then further evaluations , in particular possible manual evaluations are required , in order to determine the correct rotation direction . if the difference is larger , i . e . lies outside this hatched region , then an unambiguous evaluation of the correct rotation direction is possible . thus , it is to be recognised that in the case that the value δh is larger than zero , the first rotation direction cw is correct , and the case that the pressure difference δh is smaller than zero , the second rotation direction ccw is the correct rotation direction . this results due to the fact that the exit pressure of the pump is greater with the correct rotation direction . accordingly , in the case that the difference δq of the throughputs according to the above formula is positive , then the rotation direction cw is correct , and in the case that this difference δq is negative , then the second rotation direction ccw is correct . this results due to the fact that a greater throughput is given with a correct rotation direction of the pump . in the case that the power p as a performance characteristic value is compared , then in the case that the power difference δp according to the above formulae is larger than zero , then the second rotation direction ccw is correct , and in the case that the difference δp is smaller than zero , the first rotation direction cw is then correct . this is due to the fact that the electrical power uptake is smaller with the correct rotation direction than with the incorrect rotation direction . when rotating in the correct rotation direction , the pump has a greater efficiency and thus a lower power uptake . it is to be understood that other performance characteristic values may also be employed . in particular also the hydraulic power may be formed , and one may recognise the correct rotation direction from whether this difference is positive or negative . the rotation direction at which the hydraulic power δp hyd is greater , is the correct rotation direction . by way of fig2 , the recognition of the correct rotation direction is explained by way of two detected performance characteristic values . according to fig2 , the rotation direction recognition is effected for example by way of the pressure h and the electrical power p of the pump assembly . as described above , the difference of the pressures with both rotation directions δh and the difference of the powers δp with both rotation directions is computed according to the above formula . if then this difference δh is positive and simultaneously the difference δp is negative , then the first rotation direction cw is correct . if the power difference δp is positive and the pressure difference δh is negative , then the second rotation direction ccw is correct , wherein the difference formation was effected according to the formulae cited above with this evaluation . as is indicated in fig2 , the evaluation regions which are characterised at cw and ccw in fig2 , extend beyond the zero axis . thus the region , in which a reliable automatic recognition of the correct rotation direction is possible , is increased . the regions in which a recognition on account of measurement errors or measurement noise is not possible , is reduced in size . these regions are likewise represented hatched in fig2 . one may recognise that the tightly hatched region 2 is reduced in size in the environment of the origin . i . e . a rotation direction recognition may also take place if the pressure difference δh is close to the origin , provided that the power difference δp does not simultaneously lie in this region . vice versa , a rotation direction recognition is also possible if the power difference δp in the region 2 lies close to the origin , if simultaneously the pressure difference δh lies outside this region . a further possibility for increasing the reliability of the rotation direction recognition is possible by way of changing the rotation speed . this is represented in the fig3 a - 3 c . fig3 a - 3 c show diagrams in which the rotation speed n is represented against time t . in fig3 a , it is shown that firstly measurements of the performance characteristic values are carried out at a first rotation speed i . for this , the drive motor at the point in time t 1 is driven at the rotation speed i firstly in the first rotation direction cw , and subsequently with the same rotation speed i at the point in time t 2 in the second rotation direction ccw . simultaneously , at the points in time t 1 and t 2 , the respective performance characteristic values are determined , and are then subtracted from one another according to the preceding description , in order to recognise the correct rotation direction . if the correct rotation direction is not recognisable at the first rotation speed i , for example because the formed differences lie in the region of the measurement inaccuracy , i . e . the hatched regions in the diagrams according to fig1 and 2 , the measurement , as is shown in fig3 b , is repeated at a further rotation speed ii at the points in time t 3 and t 4 . the performance characteristic values are then again detected also at these points and the differences accordingly formed . if no recognition of the rotation direction is possible at the rotation speed ii , then the measurement , as shown in fig3 , may be repeated at a third rotation speed iii at the points in time t 5 and t 6 . it is to be understood that one may yet provide further increases in the rotation speed until the maximal rotation speed of the pump assembly is reached . a manual determining would have to be carried out should an evaluation of the correct rotation speed still not be possible then . this may be made aware to the operating person by way of a signal device for example . the procedure of the rotation direction recognition is described schematically by way of fig4 . in the step s 1 , firstly the pump assembly is operated at a first rotation speed i in a first rotation direction cw . at this rotation speed , one or more performance characteristic values are detected by the rotation direction recognition module . these may be the pressure h , the throughput q and / or the power p for example . subsequently , in step s 2 , the pump assembly is stopped , and then in step s 3 is driven at the same rotation speed i , but in the opposite rotation direction ccw . the same performance characteristic values as in step s 1 are detected with this rotation direction . then in step s 4 , the difference between the performance characteristic values computed in step s 1 and in step s 3 is formed . in step 5 , one then examines as to whether the difference is adequately large , in order to determine the correct rotation direction , i . e . the difference lies outside the region of the measurement inaccuracies , the hatched regions in fig1 and 2 . if the difference is large enough , the correct rotation direction is determined and the rotation direction of the pump assembly is set accordingly in step s 6 . this may be effected either by way of a suitable activation of a frequency converter , or by way of changing the poling of the electrical connections , wherein this too may be effected automatically by switches , in particular electronic switches in the pump assembly . alternatively , an operating person may also be signalized by a signal device , that the electrical connections need to be changed manually , in order to set the correct rotation speed . if in step s 5 , it is ascertained that the evaluated difference between the performance characteristic values is smaller than the minimal difference for determining the correct rotation direction , then either according to step s 7 , a new sequence of the measurement routine beginning with s 1 at a higher rotation speed ii may be effected , or a manual test of the correct rotation speed is prompted in step s 8 , in particular if previously the evaluation has already been effected at the maximal possible rotation speed . fig5 schematically shows the construction of the pump assembly according to the invention . the pump assembly consists of a pump 4 and an electrical drive motor 6 . moreover , a control device 8 is present for activating the pump assembly and in particular the drive motor 6 . the control device 8 is shown schematically and enlarged in fig5 . it is to be understood that the control device 8 is usefully integrated into a terminal box 10 of the pump assembly . the control device 8 comprises a frequency converter 12 and a rotation direction recognition module 14 . moreover , a display device 16 in the form of one or more signal lights or a display is provided . the control device 8 is supplied with mains voltage via an electrical connection 18 . the mains voltage is changed in its frequency via the frequency converter 12 , such that the drive motor 6 may be driven by the frequency converter 12 in the desired rotation speed and rotation direction . moreover , a sensor 22 for detecting the pressure and / or the throughput of the pump 4 is arranged at the exit side or pressure side of the pump 4 . the output signals or output values of the sensor 22 are led to the rotation direction recognition module 14 , for example via a signal lead . moreover , a sensor 24 for determining the electrical power which is supplied to the drive motor 6 , may be provided , wherein the output signal of the sensor 24 may also be led to the rotation direction recognition module 14 . it is to be understood that all these sensors or only a few of these sensors , for example the pressure sensor , the throughput sensor and / or the power sensor may be provided , and connected to the rotation direction recognition module 14 . as is described above , in principle it is sufficient to determine one performance characteristic value for detecting the rotation direction . the rotation direction recognition module 14 cooperates with the frequency converter 12 in a manner such that it instructs the frequency converter 12 with regard to the correct rotation direction , and ensures that the frequency converter 12 , on operation , drives the pump assembly or the drive motor 6 in the correct rotation direction . moreover , the rotation direction recognition module 14 may activate the frequency converter 12 during the rotation direction recognition , in a manner such that as previously described , it successively drives the drive motor 6 at a predefined rotation speed in two different rotation directions , wherein then the performance characteristic values are detected via the sensors 22 , 24 . in the case that the recognition of the correct rotation direction should not be possible , the rotation direction recognition module 14 may notify an operating person of this via the signal device 16 . instructions or steps to carry out a manual determining of the rotation direction may furthermore be given to the operating person via the signal device or the display device 16 . the display device 16 may be designed as a separate display device for the rotation direction recognition module 14 , or be a display device , such as a display for example , via which other functions of the pump assembly may also be displayed at the control device . it will be appreciated by those skilled in the art that changes could be made to the embodiments described above without departing from the broad inventive concept thereof . it is understood , therefore , that this invention is not limited to the particular embodiments disclosed , but it is intended to cover modifications within the spirit and scope of the present invention as defined by the appended claims .