Frequency Converter Operation - Grundfos SL1 Manual De Instrucciones

Pos. Description
1 Terminals for alarm relay
2 Terminals for analog and digital inputs and outputs
3 Terminals for supply voltage
Potentiometer for setting the warning limit of stator
4
insulation resistance
5 Terminals for RS-485 for GENIbus or Modbus
6 Indicator light for moisture measurement
7 Indicator light for stator insulation resistance
8 Indicator light for leakage (WIO)
9 Indicator light for vibration in pump
Terminals for measurement of stator insulation
10
resistance
11 Terminals for connection of pump sensors
12 DIP switch for configuration
13 Indicator light for motor temperature
14 Button for resetting alarms
15 Indicator light for motor running
16 Indicator light for service
17 Terminals for digital outputs

9.7 Frequency converter operation

All SL1/SLV pump types are designed for frequency converter
operation to keep the energy consumption at a minimum.
To avoid the risk of sedimentation in the pipes, we recommend
that you operate the speed-controlled pump at a flow rate above
3.28 ft/s (1 m/s).
For frequency converter operation, please observe the following
information:
• Requirements must be fulfilled.
See section
9.7.1 Requirements
• Recommendations ought to be fulfilled.
See section
9.7.2 Recommendations
• Consequences should be considered.
See section
9.7.3 Consequences
9.7.1 Requirements
• The thermal protection of the motor must be connected.
• Peak voltage and dU/dt must be in accordance with the table
below. The values stated are maximum values supplied to the
motor terminals. The cable influence has not been taken into
account. See the frequency converter data sheet regarding the
actual values and the cable influence on the peak voltage and
dU/dt.
Maximum repetitive peak voltage
[V]
850
• If the pump is an FM-approved pump, check if the FM
certificate of the specific pump allows the use of a frequency
converter.
• Set the frequency converter U/f ratio according to the motor
data.
• Local regulations/standards must be fulfilled.
9.7.2 Recommendations
Before installing a frequency converter, calculate the lowest
allowable frequency in the installation in order to avoid zero flow.
• Do not reduce the motor speed to less than 30 % of rated
speed.
• Keep the flow velocity above 3.28 ft/s (1 m/s).
• Let the pump run at rated speed at least once a day in order to
prevent sedimentation in the piping system.
• Do not exceed the frequency indicated on the nameplate.
In this case there is risk of motor overload.
• Keep the motor cable as short as possible. The peak voltage
will increase with the length of the motor cable. See data sheet
for the frequency converter used.
• Use input and output filters on the frequency converter.
See data sheet for the frequency converter used.
• Use screened motor cable if there is a risk that electrical noise
can disturb other electrical equipment. See data sheet for the
frequency converter used.
9.7.3 Consequences
When operating the pump via a frequency converter, please be
aware of these possible consequences:
• The locked-rotor torque will be lower. How much lower will
depend on the frequency converter type. See the installation
and operating instructions for the frequency converter used for
information on the locked-rotor torque available.
• The working condition of bearings and shaft seal may be
affected. The possible effect will depend on the application.
The actual effect cannot be predicted.
• The acoustic noise level may increase. See the installation
and operating instructions for the frequency converter used for
advice as to how to reduce the acoustic noise.
Maximum dU/dt U 400 V
N
[V/μ sec.]
2000
19