14
FIG. 11 – OFFSET TRIMPOT ADJUSTMENT
FIG. 12 – DEADBAND TRIMPOT ADJUSTMENT
B. Offset (OFFSET) –
This trimpot
determines the amount of bias in the
forward or reverse direction. The
trimpot is factory set to provide ap-
proximately zero offset, which
means neither the forward nor the
reverse speed is favored. (See fig.
11 which illustrates the action of the
OFFSET trimpot.)
C. Deadband (DB)
– The DB trimpot
sets the amount of main speed po-
tentiometer rotation required to initi-
ate control voltage output. It is fac-
tory adjusted to approximately 25%
of rotation.
The DB trimpot also determines the
amount of delay that will occur be-
fore regeneration starts. (Regenera-
tion occurs when the applied load
torque is in the same direction as
the motor rotation.)
To readjust the DB to factory setting:
i. Set Main Speed pot to zero
speed position.
ii. Set DB trimpot to full CCW posi-
tion.
iii. Adjust DB trimpot CW until mo-
tor hum is eliminated.
(See fig. 12 for graphic illustra-
tion of the DB trimpot.)
Note: If the deadband trimpot is set too low (CCW direction), the motor may oscillate
between forward and reverse. Adjust deadband trimpot CW until the instability
disappears. (Oscillation may also occur due to response setting. See section VIII, G, p.
15.)
D. Forward Current Limit (FWD CL) and Reverse Current Limit (REV CL) Trimpots –
These trimpots are used to set the maximum amount of DC current that the motor can
draw in both the forward and reverse directions. The amount of DC current determines
the amount of maximum motor torque in both the Speed Control Mode and Torque Control
Mode. They are factory set at 150% of the current established by the jumper J2 setting.
Readjust the CL trimpots as follows:
i. Turn CL trimpot to MIN (CCW) position. Be sure jumper J2 is in proper position
approximately equal to the motor DC ampere rating.
ii. Wire in a DC ammeter in series with armature lead. Lock shaft of motor.
iii. Apply power. Rotate CL trimpot CW until desired CL setting is reached (factory
setting is 1.5 times rated motor current). Be sure control is in Forward direction for
FWD CL trimpot adjustment and likewise with REV CL.
WARNING! Do not leave motor shaft locked for more than 2 – 3 seconds to prevent
motor damage.
CAUTION: Adjusting the CL above 150% of motor rating can cause overheating and
demagnetization of some PM motors. Consult motor manufacturer.
