C.E. Niehoff & Co. N1224 Standard Troubleshooting Guides - Manual (Page 2)

Page 2
TG0045A
Section 1: Wiring Diagram
CEN N1224-1/N1224-2/N1224-3 Alternators
Description and Operation
N1224 28 V 260 A/14 V 140 A dual voltage alterna-
tor is internally rectified. All windings and current-
conducting components are non-moving, so there are
no brushes or slip rings to wear out. Energize switch
(commonly an oil pressure switch or ignition switch)
activates regulator. Field coil is then energized when
rotation is detected. Upper voltage (28 V) is rectified
with standard diodes. Lower voltage (14 V) circuit
output current is controlled by SCRs. Alternator out-
put current is self-limiting and will not exceed rated
capacity of alternator.
N3221 regulator provided with N1224-1 alternator,
N3229 regulator provided with N1224-2 alternator,
and N3232 regulator provided with N1224-3
alternator
• are flat temperature compensated. Setpoint is 28.0
± 1.0 V and 14.0 ± 0.5 V at all temperatures.
• provide overvoltage cutout (OVCO). Regulator
will trip OVCO when system voltage rises above
setpoint by 3 V for longer than 3 seconds. OVCO
feature detects high voltage and reacts by opening
alternator field circuit and turning off alternator.
Restarting engine or waiting until system voltage
drops 5 V below setpoint will reset OVCO circuit.
• maintain alternator steady-state output voltage at
regulated settings as vehicle electrical loads are
switched on and off.
In addition, N3232 regulator provided with N1224-3
alternator
• limits alternator output to 200 A.
• automatically determines operating mode (see
Chart 5).
Figure 2 — N1224-1 Alternator with N3221 Regulator/N1224-2 Alternator with N3229 Regulator/
N1224-3 Alternator with N3232 Regulator
Figure 1 — Alternator and Regulator Terminals
T
14 V B+ terminal
B–
terminal
T
T
T
AC terminal
T
E terminal
T
28 V B+ terminal
J1939 Data bus connector
T
Alternator-to-regulator
harness
REGULATOR