5
If you do not have any of the specifications of your generator’s exciter, or if you
don’t know where to start when trying to determine your exciter specs, please
see the section below for instructions on measuring and calculating your exciter
specifications.
• Measure your exciter field resistance using a multimeter on your field leads. Record this value. If
you have a brush-type generator, also take a resistance reading on your slip rings: the value you
obtain on the slip rings should be no more than 1% difference from the value you obtained through
the field leads.
• Next, start and run the generator and apply 12V from a battery through your field leads and record
the AC voltage produced by the generator. To determine your full load exciter field voltage, use
the following formula:
E
Exc.
=
Where
E
Gen.Conf
.
is your Generator’s configured voltage (e.g.: 120, 208, 240, 480V, etc.),
E
Gen.Output
is
your recorded output voltage, and
E
Battery
is your battery voltage (12V usually).
• Next, calculate your maximum exciter field amperage using your measured field resistance and
your calculated exciter voltage using the following formula:
Where
I
is your maximum exciter field current,
E
is your calculated field voltage from the above
formula, and
R
is your measured field resistance.
Using the values you just measured and calculated, see the chart on the
previous page to determine which connection you should use to connect the
XR8 to your generator.
For Example:
Measured Field Resistance: 18Ω
Battery Voltage: 12V
Generator Configuration: 480V Wye
12V applied to the field yields 189VAC L1-L3.
E
Exc.
=
480
$%&
$'
∗ 2 = 60.95
E
Exc.
=
60.95VDC (Full-Load Voltage)
This generator would use
Connection B
.
€
E
Gen
.
Conf
.
E
Gen
.
Output
E
Battery
"
#
$
$
%
&
'
'
* 2
I
=
E
R
