British Motoring Fall 2010 : Page 28
oW-to m flowing to the gener n the generator's outp voltage is lower than battery voltage. The s ond part of the control box is properly call the voltage regulator (2k). This strengthens weakens the magnetic field in the generato according to the needs of the battery or ot electrical system components. Remember, stronger the magnetic field, the greater the voltage induced in the spinning armature. cut-out relay (2e) consists of an iron core w two layers of wires wound around the core The inner wrapping of wire is called the "s windings" and the outer wrapping is called "series windings”. The shunt windings, wh are hidden under the series windings, are c nected between the armature terminal "D" the generator and a ground terminal (usua marked "E") on the control box. This means that the internal generator 2k Voltage Regulator 2e Cut-out Relay 2n Regulator Contacts 2i Cut-out Contacts 2g Series Windings age is always impressed upon the shunt win ings. All the generator output current passe through the series windings (2g, 3g) before going to the electrical system in general. Fixed above the cut-out core is a spring arm that carries a contact (2i, 3i) which is connected to the series windings (2g,3g) of the cut-out core. Output current from the generator can only pass on to the electrical system and the battery when the cut-out con-tact arms (2i,3i) are touching. Spring tension normally holds the contacts apart so there can be no current flow in either direction. Cut-Out Relay at High/Low RPMs When the armature in the generator is spinning fast enough, (about 1000 generator RPM or 750 engine RPM) To Ammeter & Battery Terminal 3i Cut-Out Contacts F D D A 3n Regulator Contacts E F Resistance 3p Field the current in the shunt windings (3f) of the cut-out relay will generate a magnetic field strong enough to overcome the natural spring tension of the contact arm (3i) and it snaps down bringing the two contacts together. Current now flows through the series windings (3g), across the contacts and out the arm (3i), finally reaching the output terminal (usually "A") on the control box. From there, it goes on to the ammeter (if fitted) and then to the battery. This current now flowing through the series windings (3g) actually intensifies the mag-netic field around the core (3h) of the cut-out relay, and this 3h Core Field Pole 3g Series Windings 3d Field Windings 3b Brush Armature 3a Generator 3e Cut-Out Relay 3l Voltage Regulator 28 British motoring Fa l l 2 0 1 0 3k Voltage Regulator 3m Shunt Windings 3f Shunt Windings
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