Arrangement comprising a switchable longitudinal voltage source and a polarity reversal device , wherein the longitudinal voltage source has a feed-in terminal (A) for feeding in a current, a first output terminal (B) and a second output terminal (C), wherein the longitudinal voltage source is suitable for optionally switching an electrical voltage of an electrical energy store between the feed-in terminal (A) and the first output terminal (B) or between the feed-in terminal (A) and the second output terminal (C), wherein - the longitudinal voltage source has a first switch (S1), which is situated electrically between the feed-in terminal (A) and the first output terminal (B), electrically connects the feed-in terminal (A) and the first output terminal (B) in the switched-on state and electrically disconnects the feed-in terminal (A) and the first output terminal (B) from one another in the switched-off state, - the longitudinal voltage source has a second switch (S2), which is situated electrically between the feed-in terminal (A) and the second output terminal (C), electrically connects the feed-in terminal (A) and the second output terminal (C) in the switched-on state and electrically disconnects the feed-in terminal (A) and the second output terminal (C) from one another in the switched-off state, - the longitudinal voltage source has a third swich (S3), which is situated electrically in series with the energy store and forms a series circuit therewith, said series circuit being electrically connected between the two output terminals (B, C), and - the polarity reversal device is connected between the two output terminals (B, C) of the longitudinal voltage source and two conductor terminal contacts of the polarity reversal device , wherein in a first position the polarity reversal device connects the first output terminal (B) to the first conductor terminal contact and the second output terminal (C) to the second conductor terminal contact , and wherein in a second position the polarity reversal device connects the first output terminal (B) to the second conductor terminal contact and the second output terminal (C) to the first conductor terminal contact . - the longitudinal voltage source has a first switch (S1), which is situated electrically between the feed-in terminal (A) and the first output terminal (B), electrically connects the feed-in terminal (A) and the first output terminal (B) in the switched-on state and electrically disconnects the feed-in terminal (A) and the first output terminal (B) from one another in the switched-off state, - the longitudinal voltage source has a second switch (S2), which is situated electrically between the feed-in terminal (A) and the second output terminal (C), electrically connects the feed-in terminal (A) and the second output terminal (C) in the switched-on state and electrically disconnects the feed-in terminal (A) and the second output terminal (C) from one another in the switched-off state, - the longitudinal voltage source has a third swich (S3), which is situated electrically in series with the energy store and forms a series circuit therewith, said series circuit being electrically connected between the two output terminals (B, C), and - the polarity reversal device is connected between the two output terminals (B, C) of the longitudinal voltage source and two conductor terminal contacts of the polarity reversal device , wherein in a first position the polarity reversal device connects the first output terminal (B) to the first conductor terminal contact and the second output terminal (C) to the second conductor terminal contact , and wherein in a second position the polarity reversal device connects the first output terminal (B) to the second conductor terminal contact and the second output terminal (C) to the first conductor terminal contact . <EOS>