11
more rapid deceleration time, rotate the DECEL trimpot coun-
terclockwise. For longer deceleration time, rotate the DECEL
trimpot clockwise. See Figure 20.
Note:
To provide increased resolution of the ACCEL and
DECEL trimpots, 50% rotation covers 0.3 - 5 seconds.
Application Note:
On applications with high inertial loads,
the deceleration may automatically increase in time. This will
slow down the rate of speed decrease to prevent the bus volt-
age 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 should not be set to less than ten (10) seconds.
E. Slip Compensation (COMP)
– Sets the amount of
Volts/Hz/Amp to maintain set motor speed under varying
loads. The COMP trimpot is factory set for 1.5 Volts/Hz/Amp.
The slip compensation may be adjusted by the COMP trim-
pot as described below. See Figure 21.
1. Wire an ammeter in series with one motor phase.
2. Run the motor and set the unloaded speed to approxi-
mately 50%.
3. Load the motor to the rated motor nameplate current
(Amps AC).
4. Adjust the COMP trimpot so that the loaded RPM is equal
to the unloaded RPM.
5. The motor is now compensated to provide constant
speed under varying loads.
F. Current Limit with I
2
t Shutdown (CL)
– Sets the current
limit (overload), which limits the maximum current to the
motor. The current limit set point is established by the setting
of Jumper J3 and the setting of the CL trimpot. See Figure 22.
2.3
0.8
Shown Factory Set to 1.5 Volts/Hz/Amp
1.5
3
0
Volts/Hz/Amp
FIGURE 21
COMP TRIMPOT RANGE
(Shown Factory Set to 160%)
Percent of Range Setting
80
40
160
200
120
FIGURE 22
CL TRIMPOT RANGE
2.5
12.5
(Shown Factory Set to 1.5 Seconds)
1.5
5
Seconds
0.3
20
FIGURE 20
DECEL TRIMPOT RANGE
110
150
140
130
10
120
160
50
1.0
0.1
SETTING (160%)
FACTORY CL
FIGURE 23 – I
2
t TRIP TIME vs MOTOR CURRENT
NOTES:
1. The CL set point is factory set to 160% of nominal motor current.
2. I
2
t Will not trip below 120% of the CL setting.
MOTOR CURRENT (%)
I
2
t TRIP TIME
(minutes)
