Ok, let me go over a basic course here just to make sure that we are all informed and on the same page. :fineprint If everyone knows all of this, then maybe you can just ignore my ramblings.
< insert soapbox entrance here > :monkey:
Unlike your house electricity, which is Alternating Current (AC), basic automotive electricity is dependent upon chemical reaction wetcell battery current and is called Direct Current (DC). The wetcell has an advantage over the drycell (ie...flashlight battery) in that it can be "re-charged" after using some of the stored electro/chemical power.
To generate that rechargeablility voltage, you need a generator or alternator. Generators take advantage of the physical property of magnets called appropriately electro-magnetism. Which basically indicates if you move an electrical conductor (wire) thru a magnetic field, you makes the little electrons in the wire flow, this is called electrial current.
Since magnets (called field) have a North and a South pole, the direction the electrical wire (called armmature) rotated by the belt thru the magnetic field effects the direction the electrons flow.
Unlike alternators, generators don't have permanent magnets, they have DC electro-magnets called FLD. The magnetic polarity of the FLD is dependent upon the way the battery is physically connected in the metal chassis which is now an electrical conductor called GROUND. For various obscure technical reasons, certain vendors chose to ground the 6 volt battery's POSITIVE terminal.
Therefore, to make the entire tractor electrical system compatable with each other, you must POLARIZE the voltage regulator/generator. You CANNOT polarize alternators because they have built-in permanent magnets and built-in voltage regulators. Generally, once you POLARIZE, you don't have to do it again, EXCEPT when you change any of the parts (battery, generator, voltage regulator). But it doesn't hurt to do it again anytime you feel compelled ---- but there must be a problem if you are having to repolarize it everytime! Remember you have to polarize the regulator/relay that might be inline with the electrical circuit. For basic relays, you can arc the two ends together with the motor not running. I might need some additional information on your SPECIFIC application to help you further.
Can you tell me a little more?