Operating instructions

Parameterizing steps Vector Control Chassis Type Frequency Converter
476 869 4070 76 J AB-74 Siemens AG
9-38 Operating Instructions SIMOVERT MASTERDRIVES
♦
The rated frequency P107 and the rated speed P108 automatically
result in the calculation of the pole pair number P109. If the
connected motor is designed as a generator and the generator data
are on the rating plate (oversynchronous rated speed), you have to
correct the pole pair number manually (increase by 1 if the motor is
at least 4-pole), so that the rated slip (r110) can be correctly
calculated.
♦
For induction motors, you have to enter the actual rated motor
speed, and not the synchronous no-load speed in P108, i.e. the slip
frequency at nominal load has to be derived from parameters
P107...P109.
♦
The rated motor slip (1 - P108/60 x P109/P107) should usually be
greater than 0.35 % x P107.
These low values are, however, only achieved in the case of motors
with a very high rating (above approx. 1000 kW).
Motors with average rating (45..800 kW) have slip values around
2.0...0.6 %.
Motors with low rating (below 22 kW) can also have slip values up to
10 %.
♦
It is possible to achieve a more accurate evaluation of the rated slip
after standstill measurement (P115 = 2) by taking into account the
temperature evaluation for the rotor resistance P127.
On cold motors (approx. 20 °C), the value is usually around
70 % (
±
10 %) and on warm motors (operating temperature) around
100 % (
±
10 %). If there are any large differences, you can proceed
on the assumption that the rated frequency P107 or the rated speed
P108 do not correspond to the real values.
♦ If the rated motor frequency (engineered!) is below 8 Hz, you have
to set P107 = 8.0Hz in the drive setting. The rated motor voltage
P101 has to be calculated in the ratio 8 Hz / f
Mot,N
and the rated
motor speed
P108 should result in a much greater slip:
P108 = ((8 Hz - P107
old
) x 60 /
P109) + P108
old
.