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B. Maximum Speed (MAX). The MAX trimpot is used to set the
maximum output frequency of the drive. The maximum speed
is factory set to full rated motor speed. Readjust the MAX
trimpot as follows:
FIG. 13B – MAX
1. Rotate main potentiometer to maximum speed position (full
clockwise).
2. Adjust MAX trimpot to desired setting of motor speed.
C. Acceleration (ACC). The ACC trimpot sets the time it takes
the motor to reach full speed from an initial zero start.
The trimpot is factory set to approximately 1.5 seconds.
Adjust the ACC trimpot as required for the application.
See fig. 13C.
FIG. 13C – ACC
Note: When the control is set for 50 Hz operation,
the ACC trimpot will automatically change to adjustable
acceleration and deceleration.
NOTE: Rapid acceleration may cause the current limit
circuit to activate. This will automatically extend the
acceleration time.
D. Deceleration (DEC). The DEC trimpot sets the time it will take the motor to reach
zero speed from an initial full speed setting. The trimpot is factory set to approximately
1.5 seconds. Adjust the trimpot as required for application.
Note: When the control is set for 50 Hz operation, the DEC trimpot will automatically
change to Adjustable Boost. See sec. IX, G, p. 28.
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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 D.C. 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 ACC and DEC trimpots be set to a
minimum of 10 seconds.
Fig. 13D – DEC
E. Current Limit with I2t Shutdown (CL).
The CL trimpot is used to set the
maximum motor current that occurs in
FIG. 13E – CL SETTINGS (HP and 1HP )
a stalled condition. The CL trimpot is
factory set to approximately 160% of
full control rating (3.8 amps: HP,
6.8 amps: 1 HP). The CL trimpot can
be readjusted as required. See fig.
13E.
The current limit also contains an I2t
trip function. The control will trip
according to a predetermined current
versus time function. The trip curve is directly related to the CL setpoint and can be
changed with the CL trimpot. Table 6, p. 27 relates the CL setpoint to trip time.
The current limit with I2t shutdown is designed to provide motor overload protection.
Readjust the CL trimpot so that it is set to 160% of full rated motor current as follows.
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