C.E. Niehoff & Co. C717 Troubleshooting Guides - Manual (Page 2)

Page 2 TG78A
Section A: Description/Operation
CEN C717 Alternator/Regulator Description
and Operation
C717 28 V (400 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. This alternator has a maximum ambient
operating temperature of 65°C/149°F.
This alternator is externally energized when the battery
master switch on the vehicle is turned on and provides
power to the regulators through the IGN circuit (the
A2-351 regulator can also operate without vehicle con-
nection to IGN, and instead provide power by sensing
rotation through the regulator’s AC circuit).
Field coil is then energized. AC is rectified into DC out-
put through diodes in drive end rectifier housing and
supplied to the battery from the alternator B+ terminal.
See schematic diagram on page 3.
Alternator output current is self-limiting and will not
exceed rated capacity of alternator. Regulator maintains
alternator output voltage at pre-determined regulated
setting (see below for setpoints) as vehicle electrical
loads are switched on and off.
A2-351 regulator furnished with some units includes:
• External IGN terminal that can provide optional
external energize connection. This regulator can
function with or without vehicle ignition. When neces-
sary, regulator IGN terminal can be connected to
vehicle ignition source to provide battery voltage
when engine is running. Circuit should be off (no
voltage present) when vehicle ignition is off or
engine is not running.
• P terminal that can provide optional AC voltage tap.
P terminal signal frequency (Hz) x 10 = alternator
shaft rpm.
• D+ terminal that can provide DC voltage signal to
vehicle electrical system, confirming alternator
operation.
• Overvoltage cutout (OVCO). See page 4.
• Tricolored LED. See page 4.
• Battery type selection and battery maintenance/func-
tion are the sole responsibilities of the customer.
• Temperature-voltage sense/J1939 harness connector
to be used with optional harness.
— When temperature/voltage sense/J1939 harness
is not connected, regulator will operate in fixed
voltage setting determined by the select switch
position on the bottom of the regulator. See
Column 2 in Table 2.
— When temperature/voltage sense/J1939 harness is
connected, regulator will automatically optimize
the charge voltage for battery type based on temp-
erature. Also, vehicle manufacturer-requested
functions of J1939 interface are available through
connector. See Column 3 in Table 2.
Figure 2 —Voltage/Battery Switch
Table 2 — A2-351 Regulator Voltage/Battery Switch Position
Switch Position
T-VS/J1939 Harness Not
Connected (Voltage Select)
T-VS/J1939 Harness Connected
(Battery Select)
Position 1 27.5 V Maintenance (D Category)
Position 2 28.0 V Maintenance-free (Group 31)
Position 3 28.5 V AGM
Position 4 29.0 V DO NOT USE POSITION # 4