"The EP regulator, how does it work".

"The EP regulator, how does it work".
The EP regulator has the ability to detect many faults in the charging
system not previously possible with earlier types. Detection of open
circuit rotor winding is now possible. Backup regulation is provided
should a malfunction occur, this supplies usable output until service
can be obtained. Battery sensing ensures that the correct voltage is
available at the battery at all times thus compensating for resistance
in the charge cable.
Operation
The "EP" regulator has a number of operating phases, please read
the following carefully.
Start up phase.
When the Ignition switch is turned on and the engine is not running.
The internal hybrid module detects the presence of warning lamp
current, an internal oscillator running at 4 KHz and 50% duty cycle
starts up. The output from this oscillator drives the base circuit of
the regulator output transistor at its' operating frequency, about 2.5
amps of rotor current is supplied to the rotor circuit.
When the rotor commences to rotate its' magnetic field cuts the
stator winding at right angles inducing into it an AC current which is
then rectified by a three phase Zener diode bridge. As the speed is
increased the voltage at the "W" or phase connection increases.
The regulator detects this increase at the phase terminal, when the
phase voltage reaches approximately 5.8 volts the regulator turns the
oscillator off and the output transistor hard on. At this point the
warning lamp also turns off. Battery current flows from the B+
terminal through the rotor and the output transistor to ground.
Normal Regulation Phase
The output rises rapidly until the "S" terminal senses the voltage at
the battery has reached the regulator set voltage, at this point the
regulator turns off. The voltage falls, the output transistor turns on
again, the voltage rises and the cycle repeats to maintain a constant
voltage usually 14.2 volts. This voltage will vary slightly from this
figure due to temperature compensation.
The new generation EP regulators incorporate current limiting in the
warning lamp circuit to prevent lamp driver failure if a high wattage
lamp is fitted in error. 9 190 067 019/020 (RE60/RE59) have this
feature.
Backup Regulation.
The EP regulator will limit the output voltage to a safe level should
either the main B+ cable or the battery sense wire become decoupled, the output voltage will be slightly above the normal setting
(1.7 - 2.2 volts). The regulator will also enter backup mode if the
voltage drop on the charge line becomes excessive. If the regulator
enters backup mode the warning lamp will turn on. Faults such as
high resistance fusible links, dirty or loose terminals. It is possible
for the regulator to go in and out of this mode, the result will be that
the warning lamp may flash on and off.
Warning lamp failure.
Should the warning lamp fail, the alternator will self excite by
deriving a small current from the phase connection allowing the
voltage to build up to regulating level. Note: No field current will flow
when the engine is cranking.
Diagnostics
The EP regulator incorporates diagnostics which will illuminate the
warning lamp as a result of fault conditions in the alternator and
external circuitry.
These conditions include:
1
2
3
4
5
6
An open circuit in the regulator battery sensing wire
( S Terminal).
An open circuit or excessive voltage drop in the B+ cable.
An open circuit in the alternator phase connection.
Overcharging of the battery.
Regulator output stage short circuit.
Open circuit rotor.
The regulator compares the voltage at B+ with the voltage at the "S"
terminal connected to battery positive. If the voltage differential
exceeds a predetermined threshold, the regulator will operate in
backup mode to limit the output voltage to a safe level. The warning
lamp will remain illuminated as long as these conditions prevail.
Sources of high resistance which will trigger the warning lamp are:
a
b
c
d
Dirty battery terminals.
Poor contact in wiring harness connectors.
Poor contact between rectifier and regulator.
High resistance in fusible link assembly.
Caution:
When bench testing the alternator it is important that the warning
lamp wattage of 2 watts is not exceeded. Reversal of the "S" and "L"
on the regulator will damage the regulator.
The correct plug for the regulator is 9 122 067 011 for the Bosch type
and for the Shinagawa connector the number is X 02 FW.