Specifications

23
FIGURE 21 – CURRENT
LIMIT TRIMPOT RANGE
FIGURE 22 – I
2
T TRIP TIME vs.
MOTOR CURRENT
The slip compensation may be adjusted as follows:
A. Connect an AC RMS ammeter in series with one motor phase.
B. Run the motor and set the unloaded speed to
approximately 50% (900 RPM on 4-pole 1500/1725 RPM motors).
C. Using a tachometer, record the unloaded speed.
D. Increase motor loading until motor current is equal to the nameplate rated current
(AC Amps).
E. Adjust the COMP Trimpot until the loaded RPM is equal to the unloaded RPM.
The motor is now compensated to provide constant speed under varying loads.
7.6 MOTOR OVERLOAD (I
2
t) WITH RMS
CURRENT LIMIT (CL)*: Sets the current limit
(overload), which limits the maximum current to
the motor, preventing motor burnout and
eliminating nuisance trips. The CL Trimpot is
factory set to 160% of the drive rated current. To
increase the current limit, rotate the CL Trimpot
clockwise. To decrease the current limit, rotate
the CL Trimpot counterclockwise. See Figure
21.
Figure 22, shows the I
2
t Trip Time vs. Motor Current. Also see Section 5.2, on page 17.
*UL approved as an electronic overload protector for motors.
CAUTION!
If the current limit is adjusted above 160% of the motor nameplate rating,
this can cause overheating of the motor.
CAUTION!
Do not leave
the motor in a locked
rotor condition for more
than a few seconds since
damage may occur.
Notes: 1. In order to
ensure that the motor is
properly protected with
the I
2
t feature, it is
required that the CL
Trimpot be set for 160%
of the motor nameplate
rated current, as
described above. 2. This
adjustment must be
made within 6 seconds
or the I
2
t Trip will occur.