KB Electronics KBVF-48 - Manual (Page 25)

13.6 BOOST (DEC/B) – When the drive is set for 50 Hz Motor
Operation (Jumper J1 installed in the “50Hz” position), the
DEC/B Trimpot automatically becomes the adjustable
BOOST Trimpot.
Most 60 Hz motors conforming to NEMA standards can
operate from a preset Volts/Hz curve. 50 Hz motors, how-
ever, generally differ widely in their characteristics.
Therefore, it is necessary to have adjustable Boost to
obtain maximum motor performance.
To increase the boost, rotate the BOOST Trimpot clock-
wise. To decrease the boost, rotate the BOOST Trimpot
counterclockwise. See Figure 35.
In order for the 50 Hz motor to run properly, the boost
must be adjusted. If the application does not require full
torque below 10 Hz, the Boost (DEC/B) Trimpot can be
conservatively set at 8% (9 o’clock position).
Note: In 50 Hz motor operation, the deceleration time is
automatically set to the same as the Acceleration Trimpot
(ACC) setting.
WARNING! To avoid motor winding heating and
failure, do not overboost the motor.
The Boost (DEC/B)Trimpot may be adjusted as follows:
1. Wire an AC RMS ammeter in series with one motor
phase.
2. Run the motor unloaded at approximately 4 Hz
(or 120 RPM).
Note: An unloaded motor with excessive boost will
draw more current than a partially loaded motor.
3. Increase the boost until the ammeter reaches the
nameplate rated current (Amps AC).
4. Using the Main Speed Potentiometer, slowly adjust the
motor speed over a 0 – 15 Hz (0 – 450 RPM) range. If
the motor current exceeds the nameplate rating,
decrease the boost setting.
13.7 MOTOR OVERLOAD (I 2 t) WITH RMS CURRENT LIMIT
(CL)* – Sets the current limit (overload), which limits the
maximum current to the motor, prevents motor burnout,
and eliminates 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 Figures 36 – 39,
on pages 25 and 26.
*UL approved as an electronic overload protector for motors.
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 rating. This is accomplished as follows:
25
(Shown Factory Set to 5 Volts/Hz)
5
DEC/B
0 30
8
15
23
FIGURE 35 – BOOST TRIMPOT RANGE
ALL MODELS
(Shown Factory Set to 10.7 Amps)
4.0
CL
12.5
6.1
8.3
10.7
FIGURE 36 – CL TRIMPOT RANGE
MODEL KBVF-27
(Shown Factory Set to 14.4 Amps)
17.0 5.5
CL
7.4
9.8
14.4
FIGURE 37 – CL TRIMPOT RANGE
MODEL KBVF-29
(Shown Factory Set to 7.4 Amps)
8.5 3.0
CL
4.4
5.8
7.4
FIGURE 38 – CL TRIMPOT RANGE
MODEL KBVF-45