KB Electronics KBAC-29 (1P) - Manual (Page 25)

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12.8 BOOST (BOOST) – The drive is factory set for Fixed Boost (Jumper J6 set to the “FIX” position).
When the drive is set for Adjustable Boost (Jumper J6 set to the “ADJ” position), the BOOST Trimpot
can be used to adjust the amount of boost voltage to the motor. See Figure 38, on page 25. Also see
Section 6.5, on page 18.
Application Note – The Boost function operates over a frequency range of 0 – 15 Hz. If the frequen-
cy range required is above 15 Hz, Boost adjustment is not necessary.
12.7 MOTOR OVERLOAD (I 2 t) WITH RMS CURRENT LIMIT (CL)* – Sets the current limit (overload),
which limits the maximum current to the motor, which prevents motor burnout and eliminates nui-
sance 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 counter-
clockwise. See Figure 36, on page 23, and Figure 37.
*UL approved as an electronic overload protector for motors.
CAUTION! Adjusting the current limit above 160% of the motor nameplate rating can cause overheat-
ing of the motor. Consult the motor manufacturer. Do not leave the motor in a locked rotor condition
for more than a few seconds since motor damage may occur.
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 below.
Note: This adjustment must be made within 6 seconds or the I 2 t Trip will occur.
The current limit may be adjusted as follows:
1. Connect an AC RMS ammeter in series with one motor phase.
2. Set the CL Trimpot fully counterclockwise.
3. Adjust the speed setting to 30%.
4. Lock the motor shaft and adjust the CL Trimpot to 160% of the motor nameplate rated current.
Tr
ip
Time (Minutes)
CL (Factory Setting)
140 110 120 130
0.1
Motor Current (%)
1
160 150
10
100
1000
FIGURE 37 – I 2 t TRIP TIME VS . MOTOR CURRENT