14
the motor armature voltage. If the tach-generator polarity is reversed, the motor will
accelerate to full speed and the Main Speed Potentiometer will not control speed. Tach-
generator feedback can greatly improve speed regulation and dynamic response.
Note:
When using a tach-generator, the IR trimpot should be set fully counterclockwise.
Note:
The tach-generator input is designed for 7 Volt or 50 Volt per 1000 RPM tach-gen-
erators used with 1800 RPM motors. For a tach-generator other than 7 Volt or 50 Volt
per 1000 RPM or for motors other than 1800 RPM, an external 1/2 Watt resistor (RT)
must be installed. Install RT in series with the tach-generator, as shown in Figure 16.
Jumper J3 must be set to the “7V” position.
The value of RT in Ω can be calculated using the following formula:
RT = (4.37 X VT X S) - 55000
Where VT is the tach-generator voltage (in Volts per 1000
RPM) and S is the base speed of the motor (in RPM).
Example:
Suppose you have a 20 Volt per 1000 RPM tach-generator with a 3600 RPM motor.
RT = (4.37 X 20 X 3600) - 55000 = 259640
Choose the closest 1/2 Watt resistor value, which is 240000 (240k) or 270000 (270k).
Readjustment of the MAX trimpot may be necessary to achieve the desired maximum
output voltage.
III.
SETTING SELECTABLE JUMPERS
The KBRC-240D has selectable jumpers which must be set before the control can be used.
See Figure 1, on page 7, for location of jumpers.
A. AC Line Input
Voltage
Selection (J1
and J2) –
Jumpers J1
and J2 are
both factory
set to the
“230V” position
for 208/230
Volt AC line input. For 115 Volt AC line
input, set
both
Jumpers J1 and J2 to the
“115V” position. See Figure 17.
B. Motor Voltage Selection (J3) –
Jumper
J3 is factory set to the “A180” position for
180 Volt motors. For 90 Volt motors, set
Jumper J3 to the “A90” position. See
Figure 18.
RELAY
T-
T+
TB3
G
DC TACH-GENERATOR
-
+
FIGURE 15 – DC TACH-GENERATOR
CONNECTION
R
T
T+
RELAY
T-
TB3
G
DC TACH-GENERATOR
+
-
FIGURE 16 – DC TACH-GENERATOR
CONNECTION WITH ADDITION OF RT
Control Set for 208/230 Volt AC Line Input
(Factory Setting)
Control Set for 115 Volt AC Line Input
J1 Set for 208/230
Volt AC Line
J2 Set for 208/230
Volt AC Line
J1 Set for 115
Volt AC Line
J2 Set for 115
Volt Ac Line
J1
230V 115V
J2
115V 230V
J1
230V 115V
J2
115V 230V
FIGURE 17 – AC LINE INPUT VOLTAGE SELECTION
J3 Set for 90 Volt Motor
J3 Set for 180 Volt Motor
(Factory Setting)
T50
T7
A90
A180
J3
T50
T7
A90
A180
J3
FIGURE 18 – MOTOR VOLTAGE
SELECTION
