C.E. Niehoff & Co. N1245/N1248-3 Troubleshooting Guides - Manual (Page 2)

Page 2 TG44D
Section A: Wiring Diagrams
Figure 2 — N3044 Regulator Terminals
CEN N1245 Alternator
Description and Operation
N1245 28 V (260 A) alternator is internally rectified.
All windings and current-transmitting components are
non-moving, so there are no brushes or slip rings to
wear out. Energize switch activates regulator. Field coil
is then energized.
When controlled by the
N3043 regulator, this alternator
becomes self-energizing through internal diode trios.
Residual magnetic field induces small voltage in stator
and energizes field coil. Field coil continues receiving
incremental voltage until full voltage is achieved. AC is
rectified into DC output through diodes. Regulator con-
trols voltage output. N3043 regulator has a D+ terminal
to provide signal to vehicle electrical system, confirming
alternator operation.
When controlled by the
N3044 or N3261 regulator,
after engine is running, regulator receives energize
signal through IGN terminal. Regulator monitors alter-
nator rotation and provides field current only when it
detects alternator shaft rotating at or above idle speed.
After regulator detects alternator rotation, it gradually
applies field current, preventing an abrupt mechanical
load on accessory drive system. The soft start may take
up to 20 seconds.These regulators are flat temperature
compensated. These regulators have:
• P terminal that can provide optional AC voltage tap.
• D+ terminal to provide optional signal to vehicle
electrical system, confirming alternator operation.
• Tricolored LED on N3261 only. See page 6.
Figure 1 — N1245/N1248-3 Alternator Terminals
(N3043 Regulator Attached to Alternator)
B+ terminal


D+ terminal
B– terminal

Figure 3 — N3261 Regulator Terminals
P terminal


D+ terminal

IGN terminal
P terminal


D+ terminal

IGN terminal
CEN N1248-3 Alternator
Description and Operation
N1248-3 28 V (310 A) alternator is internally rectified.
All windings and current-transmitting components are
non-moving, so there are no brushes or slip rings to
wear out. Energize switch activates regulator. Field coil
is then energized.
When controlled by the
N3043 regulator, this alternator
becomes self-energizing through internal diode trios.
Residual magnetic field induces small voltage in stator
and energizes field coil. Field coil continues receiving
incremental voltage until full voltage is achieved. AC is
rectified into DC output through diodes. Regulator con-
trols voltage output. N3043 regulator has a D+ terminal
to provide signal to vehicle electrical system, confirming
alternator operation.