Adjusting The Voltage / Frequency (V/F) Characteristics; Motor Thermistor Connection - ABB ACS255 User Manual

Parameters in the Long parameter mode
Index Name/Selection
53 COMMUNICATIONS
PARAMETERS
5302 SERIAL
COMMUNICATIONS
CONFIGURATION
99 START-UP DATA
9902 DIGITAL INPUTS
FUNCTION SELECT
9905 MOTOR RATED VOLTAGE
110V/230V rated drives
0...255V
400V rated drives
0...500V
9906 MOTOR RATED CURRENT
0.2*drive rated output
current...1.0*drive rated
output current
9907 MOTOR RATED
FREQUENCY
25...500Hz
9908 MOTOR RATED SPEED
0...30000 Rpm

10.5. Adjusting the Voltage / Frequency (V/f) characteristics

9905
2610
Frequency

10.6. Motor Thermistor Connection

1 : + 24 Volt
4 : External Trip
Description
This parameter has three sub settings used to configure the Modbus RTU Serial
Communications. The Sub Parameters are :
Drive Address : Adr 0 to Adr 63
Baud Rate : 9.6kbps to 115.2kbps
Watchdog Timeout : 0 (Disabled, 300, 3000 milliseconds)
Application macros. Definition of motor set-up data.
As shown in the table below Parameter 9902 has a number of pre-programmed parameter
sets (and terminal functions) which the user selects to best suit the application.
Defines the function of the digital inputs depending on the control mode setting in
Parameter 1103 PRIMARY COMMAND SOURCE MODE. See Application macros on page 28.
This parameter should be set to the rated (nameplate) voltage of the motor (Volts).
Voltage
Note : The stress on the motor insulation is always dependent on the drive supply voltage.
This also applies in the case where the motor voltage rating is lower than the rating of the
drive and the supply of the drive.
This parameter should be set to the rated (nameplate) current of the motor.
Current
This parameter should be set to the rated (nameplate) frequency of the motor
Frequency
This parameter can optionally be set to the rated (nameplate) rpm of the motor. When set
to the default value of zero, all speed related parameters are displayed in Hz, and the slip
compensation for the motor is disabled. Entering the value from the motor nameplate
enables the slip compensation function, and the ACS255 display will now show motor speed
in estimated rpm. All speed related parameters, such as Minimum and Maximum Speed,
Preset Speeds etc. will also be displayed in Rpm.
The V/f characteristic is defined by several parameters as follows :-
Parameter 9905 : Motor Rated Voltage
Parameter 9907 : Motor Rated Frequency
The voltage set in parameter 9905 is applied to the motor at the frequency set Under
normal operating conditions, the voltage is linearly reduced at any point below the
motor rated frequency to maintain a constant motor torque output as shown by the
line 'A' on the graph.
By using parameters parameter 2610 and 2611, the voltage to be applied at a particular
frequency can be directly set by the user, thereby altering the V/F characteristic.
Reducing the voltage at a particular frequency reduces the current in the motor and
hence the torque and power, hence this function can be used in fan and pump
applications where a variable torque output is desired by setting the parameters as
follows :-
Parameter 2610 = 9905 / 4
Parameter 2611 = 9907 / 2
2611 9907
This function can also be useful if motor instability is experienced at certain
frequencies, if this is the case increase or decrease the voltage (Parameter 2610) at the
speed of instability (Parameter 2611).
For applications requiring energy saving, typically HVAC and pumping, the energy
optimizer (Parameter 2601) parameter can be enabled. This automatically reduces the
applied motor voltage on light load.
The motor thermistor should be connected between terminals 1 and 4 as shown. A
setting of Parameter 9902 where Digital Input 3 is programmed for 'External Trip' must
be used. The current flow through the thermistor is automatically controlled to
prevent a failure.
41
Def
1
1
Drive Rating
Dependent
Drive Rating
Dependent
60Hz
0 Rpm