Accel, Dec el, Comp – KB Electronics KBMA-24DF User Manual
Page 22
11.2 MAXIMUM SPEED (MAX) – Sets the maximum speed of the motor. The
MAX Trimpot is factory set for 100% of frequency setting. For a lower maxi-
mum speed setting, rotate the MAX Trimpot counterclockwise. For a higher
maximum speed setting, rotate the MAX Trimpot clockwise. See Figure 18.
11.3 ACCELERATION (ACCEL) – Sets the amount of time for the motor to
accelerate from zero speed to full speed. The ACCEL Trimpot is factory
set to 1.5 seconds. For a longer acceleration time, rotate the ACCEL
Trimpot clockwise. For more rapid acceleration, rotate the ACCEL Trimpot
counterclockwise. See Figure 19.
Note: Rapid acceleration settings may cause the current limit circuit to
activate, which will extend the acceleration time.
11.4 DECELERATION (DECEL) – Sets the amount of time for the motor to
decelerate from full speed to zero speed. The DECEL Trimpot is factory
set to 1.5 seconds. For longer deceleration time, rotate the DECEL Trimpot
clockwise. For more rapid deceleration, rotate the DECEL Trimpot counter-
clockwise. See Figure 20.
Application Note – On applications with high inertial loads, the deceleration
may automatically increase in time. This will slow down the rate of speed of
decrease to prevent the bus voltage from rising to the Overvoltage Trip
point. This function is called Regeneration Protection. It is recommended
that for very high inertial loads that both the ACCEL and DECEL Trimpots
be set to greater than 10 seconds.
11.5 SLIP COMPENSATION (COMP) – Sets the amount of Volts/Hz to maintain
set motor speed under varying loads. The COMP Trimpot is factory set to
1.5 Volts/Hz, which provides excellent speed regulation for most motors.
To increase the slip compensation, rotate the COMP Trimpot clockwise.
To decrease the slip compensation, rotate the COMP Trimpot counterclock-
wise. See Figure 21.
The slip compensation may be adjusted as follows:
1.
Connect an AC RMS ammeter in series with one
motor phase.
2.
Run the motor and set the unloaded speed to approximately 50%
(900 RPM on 4-pole 1500/1725 RPM motors).
3.
Using a tachometer, record the unloaded speed.
4.
Load the motor to the nameplate rated current (AC Amps).
5.
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.
11.6 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.
22
110
100
90
75
70
80
MAX
FIGURE 18 – MAXIMUM SPEED
TRIMPOT RANGE
(Shown Factory Set to 100%
of Frequency Setting)
ACCEL
3 1.5 0.3
10
17
20
FIGURE 19 – ACCELERATION
TRIMPOT RANGE
(Shown Factory Set to 1.5 Seconds)
DEC
EL
3 1.5
10
0.3
17
20
FIGURE 20 – DECELERATION
TRIMPOT RANGE
(Shown Factory Set to 1.5 Seconds)
COMP
1.5
0.8
0
2.3
3
FIGURE 21 – SLIP COMPENSATION
TRIMPOT RANGE
(Shown Factory Set to 1.5 Volts/Hz)