AC generator and regulator/rectifier fault finding

To make it easier for you to find faults on motorcycles with AC generators, we will describe the methods and ways to check them.

The regulator (RR) and generator can be checked according to the instructions: electrical_fault_finding.pdf.

   Rules for preventing regulator failure:

• The battery must be in good condition, i.e. it must be able to receive electricity from the generator.
• The regulator must not be covered and must be in a place with good ventilation
• The nominal current of the regulator must be equal to or greater than the production capacity of the generator
• The regulator should be securely connected to the battery with non-oxidized screws and nuts
• Never disconnect the battery while the engine (generator) is running and do not attempt to start the motorcycle without the battery

  Recommendations for the placement of the regulator:

• Never attach the regulator to the insulation, because that side of the regulator will conduct less heat
• It is even better to move the regulator 3 mm away from the substrate than to attach it to the insulation or sheet metal (so that there is air flow)
• Never install the regulator in a closed space because the temperature can increase significantly and it will definitely fail
• Do not install the regulator in a place where it is hit by hot air from a machine or a refrigerator
• Do not install the regulator in a place where it will be hit by water and dirt from the wheels
• Do not wash the regulator with a high pressure washer
  
  Checking the generator:

 

• The generator winding must not have any electrical connection with the housing (which is possible in case of failure). It is best to test the insulation at 1000VDC according to the case. The insulation should be greater than 10MR and independent of the test voltage and polarity. The insulation resistance can decrease with heating, so the resistance can drop from 1000MR to 100MR (measured with 1000VDC). In the absence of a tester, you can use an analog DC voltmeter and a diode to test for possible breakdown up to 300V:

 

• Disconnect the regulator from the AC generator
• Set the analog instrument to 300VDC. You don't even do this with a digital DC voltmeter.
• Connect the plus end of the instrument to the phase of the mains supply 220VAC
• Ground the generator (motor) housing
• Connect the diode to the minus end of the instrument so that its anode is connected and its cathode is free
• Then connect the cathode of the diode (the anode is at the minus end of the DC voltmeter) to one of the ends of the AC generator
• If the insulation is fine, the voltmeter pointer will just twitch and return to zero
• If the voltmeter reads anything other than zero volts, a generator insulation problem should be suspected

• Check the coil resistance. If it is three-phase, there must be approximately the same resistance between all three leads. If it is double single-phase, then both windings must be approximately the same value.
• Any penetration towards the case can cause a malfunction of the regulator. A breakdown can sometimes be detected by measuring the DC voltage (in millivolts) from the winding to the case. If there is some small DC voltage, and changing the voltmeter terminals also changes the polarity of the measured voltage, this indicates the possibility of a breakdown to the case. The voltmeter should read 0mV.
• If you have an AC/DC current clamp, you can test the insulation in operation:
  
  

• Connect a DC clamp around all three output wires from the generator
• Start the engine and test at different revs
• The display should be 0.00A. Repeat the same on the alternating area. If there is current shown by the current clamp, this is a sure indication that your generator has a breakdown to the case. A small AC current (less than 1mA) will flow due to the capacitance of the coil to the case.

• With an ordinary AC ammeter, you can confirm the breakdown of the generator to the case:

 

• Disconnect the regulator from the generator
• Connect an AC ammeter (20A) from one terminal of the AC generator to the case
• Start the motorcycle engine
• The measured current must be less than 1mA (the area should remain 20A!)
• Repeat the same on the remaining two leads, and also repeat everything when the generator is warmed up

• If you don't have an ammeter, you can simply try:

 

• Disconnect the regulator from the generator terminals
• Start the engine and rev up
• Try short-circuiting the output of the generator to the housing. If there is no spark when connecting and disconnecting, the generator may be good
• An even better experiment is to short-circuit one output via a weak fuse (63mA) to the housing (be careful, the regulator should be separated from the generator). If the fuse does not burn when testing at various revolutions and with a warmed-up machine, then the insulation is certainly ok. The advantage of this method is that the fuses are cheap and you can easily perform them.

Possible errors related to the AC generator:

 

• Overheating of the regulator and stop of battery charging - check the insulation of the generator
• Overheating of the regulator and a short circuit in the regulator, after which the current from the battery can destroy the windings - replace the regulator and repair the generator windings
• Frequent breakdown of the regulator - check if the three-phase winding has an accidental break in one phase (or gives a lower voltage)
• The generator windings are partially broken and the generator gives an asymmetrical and lower voltage - repair the generator
• The generator winding is broken into the housing with possible damage to the regulator - repair the generator windings and check the regulator
• The factory new regulator burns out quickly - the insulation of the generator windings or the quality of the new regulator can be suspected, i.e. the new regulator can be of lower quality than required (weaker elements in the newer version).

 

Possible errors related to the regulator:

 

• Too high or too low voltage on the battery - replace the regulator, check the quality of the battery
• After warming up the machine, the battery charges poorly - the regulator changes the characteristic
• Too low voltage on the battery - increase in voltage loss due to bad connections of the installation from the generator through the regulator to the battery. There may also be a burning of the connector that leads the current to the regulator. It is necessary to check the voltage drop dU1 and dU2 with a DC voltmeter, and that at increased throttle. They must be less than 0.3VDC on the plus line and less than 0.1V on the minus line. In practice, it is good that the voltage drop is not greater than 0.26VDC on the plus line and less than 0.06V on the minus line . This error is common with smaller installation wires. There is also an instruction for a quick solution to the problem of voltage drop to the battery.

    Another sure way to confirm the problem with bad connections from the plus and minus of the regulator to the plus and minus of the battery is to temporarily connect the plus and minus of the regulator directly to the plus and minus of the battery with 2.5mm2. The existing positive input to the regulator should be left unconnected and isolated. In doing so, a problem can arise if the regulator also has a plus wire contact. It should also be connected temporarily to the battery plus. The connections must be tight because losing the connection while the generator is running can destroy the regulator.

   If the regulator works well with direct connections, then it is necessary to solve the transient resistances in the installation or leave the direct connection with the installation of an additional 30A fuse in the circuit of the connection to the battery plus. If there is a contact + wire, then it is possible that leaving it on a permanent plus will create a battery drain. It should be taken into account that the regulators usually measure the battery voltage on that wire. In the event that the contact+ wire is left on a bad installation, it can signal the regulator that the voltage is too low, and then the battery voltage will increase. A voltage over 15V will surely destroy the battery.

Possible problems when using the SPER regulator:

 

• Too high voltage on the battery - breakdown of the generator on the housing, weakened battery, with the SPER SP regulator, too high voltage (over 15.5V) over 8000rpm indicates a failure of the parallel regulator
• Excessive battery voltage at high throttle - use of a standard series regulator instead of the HVSP regulator or failure of the parallel regulator
• Too low voltage on the battery - disconnection of one of the phases of the 3F generator or bad connection of the battery circuit (connectors, main fuse), excessive current consumption, weakened generator, too high transition resistance from the regulator to the battery, regulator failure

 

After unprofessional repair of the generator, the following errors are also possible:

 

• The regulator charges poorly, often fails - the generator is wound with a thicker wire
• Insufficient power of the generator, the windings burn out again - the generator is wound with a thinner wire - it must be the same within a hundredth of a millimeter
• The generator burns out quickly - the windings are not made with double-lacquered wire for high temperature and (or) are not baked (impregnated)

 

Errors related to the battery:

 

• Burnout regulator - bad battery, bad connections from the regulator to the battery, e.g. at the fuse between the regulator and the battery, rusty terminals
• The regulator charges poorly - failure of the regulator due to overheating, bad connection of the battery on the terminals or the main charging fuse
• The battery is weak - the regulator charges at less than 14V or at more than 15V, bad connection of the battery at the terminals or charging fuse
• The battery permanently draws a higher current with too low a voltage on the battery - a fault in the battery

 

 

Recommendations for the battery:

 

• Check the loss of current from the battery when the ignition is off. If there is, check if the loss is working with the regulator. If the motorcycle will not be in operation for a long time, disconnect the minus terminal of the battery so that it does not discharge.
• If you intend to use the motorcycle after a long break, be sure to put the battery on the charger for 14 hours.
• Screws and clamps must not be rusty or oxidized.
• The clamp must fit well over the entire surface.
• The squareness of the wire on the terminal must not be reduced due to cracking or oxidation
• If the battery has cells with caps, check the electrolyte level and add distilled water as needed
• The battery should have 14V when the regulator stops charging (minimum 13.85V).
• The regulator should be connected directly to the battery. If there happens to be a fuse, be sure that it will not lose its connection under any circumstances due to vibration or any other reason except when the current is too great. Breaking that fuse will surely destroy the regulator. The fuse has the sole purpose of interrupting the current from the battery so that it does not melt the generator winding or the windings of the electric starter. That fuse must be for a much higher than normal current.

 

 

Checking the regulator:

 

• There must be no conduction between the input AC wires
• In parallel regulators, there is a diode from each AC wire (Anode) towards the positive battery (Cathode). Also, there is a diode from the minus battery (Anode) to each AC wire (Cathode). Diodes when checking lead in the direction of Anode+, Cathode-. In the reverse direction, it must not have conductivity.
• In the case of SPER series regulators, the diodes from the battery minus to each AC input wire have been replaced with thyristors, and they do not show conductivity in the ohmic test.

 

 

Facts about parallel regulators:

 

• If the generator voltage is sufficient to charge the battery, the generator will always be loaded either by charging the battery or by a parallel short circuit via the thyristor in the regulator
• The higher the number of revolutions of the engine, the generator can provide more and more current, and the windings of the generator and the regulator will heat up more
• Regardless of the parallel voltage regulation, you must not connect the regulator only to the generator (without a battery) because the regulator will be destroyed when the generator is running.
• The parallel regulator can be destroyed when the machine reaches a high number of revolutions, and the regulator is not exposed to air flow for a long period (over 5 minutes).

 

Scheme for testing the regulator/rectifier on the table:

 

According to the diagram below, you can test the operation of single-phase and three-phase 14V regulators (with or without contact wire) on the table.

     The light shows the current flowing through the regulator. By raising the voltage with the potentiometer on the battery simulation, the light bulb should light up completely. When this happens, it is the maximum charging voltage of the battery. With our series thyristor regulators, the light should go out. If it is about HVSP regulators, the lamp should illuminate maximally over 14.7VDC voltage on the battery simulation. When it is a three-phase regulator, two phases are tested, and the free third can remain in the air or be connected to another phase with a wire.

 

    A correct parallel regulator must maintain 14.5 to 14.7V voltage while the bulb should be half bright or flashing. As a test, you can try connecting an additional load to the output of 100 Ohms (W). If it overcharges, the voltage at the output will start to rise uncontrollably above 15V and should be stopped immediately. If it is not charging enough, it will regulate the voltage to less than 13.7VDC. It is possible that the regulator on the table charges to 14.7V, and does not give the motorcycle more than 13.6V. The reason is in the resistance of the installation (wires, fuses, terminals, connections), resistance in the regulator itself, where part of the voltage remains, or poor filtering of the measured voltage in the regulator, and it is then more sensitive to voltage jumps that occur on the resistance of the installation.

 

   The electrolyte must have a large capacity in order to be able to take all the current from the source (transformer) without a large voltage jump (very important for testing our serial regulators) and accurately measure the regulated voltage.

 

    Note: do not increase the voltage of the simulated battery over 16V on the factory regulators, so as not to destroy them.