Emerson 2404 - Motor 2 Stator Resistance; Motor 2 Voltage Offset; Motor 2 Transient Inductance

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Advanced parameter
descriptions
194 Commander SK Advanced User Guide
www.controltechniques.com Issue Number: 9
This parameter contains the stator resistance of the machine for open loop vector mode operation.
If the drive cannot achieve the necessary current levels to measure the stator resistance during an auto-tune (e.g. there is no motor connected to the
drive) an rS trip will occur and the value in Pr 21.12 remains unchanged. If the necessary current levels can be achieved but the calculated resistance
exceeds the maximum allowable value for that particular drive size, an rS trip will occur and Pr 21.12 will contain the maximum allowable value.
Due to various effects in the drive inverter a voltage offset must be produced before any current flows. To obtain good performance at low frequencies
where the machine terminal voltage is small this offset must be taken into account. The value shown in Pr
21.13 is this offset given in line to line rms volts.
It is not possible for the user to measure this voltage easily, and so the automatic measurement procedure should be used (see Pr
5.14 on page 79).
With reference to the following diagram, the transient inductance is defined as
σL
s
= L
1
+ (L
2
.L
m
/ (L
2
+ L
m
))
Based on the parameters normally used for the motor equivalent circuit for transient analysis, i.e. L
s
= L
1
+ L
m
, L
r
= L
2
+ L
m
, the transient inductance
is given by:
σL
s
= L
s
- (L
m
2
/ L
r
)
The transient inductance is used as an intermediate variable to calculate the power factor.
21.12 Motor 2 stator resistance
Coding
Bit SP FI DE Txt VM DP ND RA NC NV PT US RW BU PS
3 1 111
Range 0.000 to 65.000 Ω
Default 0.000
First motor
parameter
Pr 5.17
Update rate Background
21.13 Motor 2 voltage offset
Coding
Bit SP FI DE Txt VM DP ND RA NC NV PT US RW BU PS
1 1 111
Range 0.0 to 25.0 V
Default 0.0
First motor
parameter
Pr 5.23
Update rate Background
21.14
Motor 2 transient inductance (σL
s
)
Coding
Bit SP FI DE Txt VM DP ND RA NC NV PT US RW BU PS
21 111
Range 0.00 to 320.00 mH
Default 0.00
First motor
parameter
Pr 5.24
Update rate Background
R
1
jwL
1
jwL
2
R
2
/sjwL
m
Steady state per phase equivalent circuit
of an induction motor