Operation with a static frequency converter
C-2
WILO EMU 3.0
EMC
In order to comply with EMC (electromagnetic compatibility) regulations, it may be necessary to use
shielded wires, lay cables in metal tubes and install filters. The exact actions required to comply
with the EMC directives depend on the converter type, converter manufacturer, length of cable laid
and other factors. In individual cases it is therefore necessary to look up the actions to be taken in
the converter operating manual or contact the manufacturer directly.
Motor protection
As well as the built-in electrical current monitor system in the converter, or the thermal relay in the
switching system, we recommend installing temperature sensors in the motor. Cold conductor
temperature sensors (PTC) and resistor temperature sensors (PT 100) are both suitable.
Explosion-proof motors (whose type code has the addition “Ex”) must
always be fitted with cold-type thermistors in frequency conversion
mode. Also, an approved motor protection relay for cold-type ther-
mistors (such as MSS) must be used.
Operation up to 60 Hz
A WILO submersible motor can be adjusted up to 60 Hz provided the motor has been rated for the
pump’s higher power requirement. However, the rated power should be taken from the 50 Hz data
sheets.
Efficiency
As well as the efficiency of the motor and the pump, the efficiency of the converter (approx. 95 %)
must also be taken into account. The efficiency of all components is lower when the speed is
reduced.
Formulas
Summary
As long as all these points are taken into account and the instructions for the converter are fol-
lowed, speed-regulated operation with WILO products is possible without any problems.
Pump flow
Pump head
Power
Table C-1: Formulas
Q2 = Q1 * n2
n1
H2 = H1 * n2
n1
2
P2 = P1 * n2
n1
3
