Operating instructions
49
REMARK
Current measuring in not-controlled phases
Thyro-P 2P
Although phase 2 is not controlled in Thyro-P 2P, it is possible to take measuring values during this
phase. A current transformer corresponding to T1 must be used and burdened (see type overview).
It is connected as in table 23 to X7.1.22 – X7.2.21.
Thyro-P 1P
As only phase 1 is controlled with Thyro-P 1P, the measuring systems of phase 2 and 3 can be used
freely. The corresponding current transformers (with max. 1V at nominal current) must be applied
and burdened. Connection is carried out as in table 23 to terminal strips X7.1.22 – X7.2.21 for
“phase 2”, and to X7.1.32 – X7.2.31 for “phase” 3.
The measuring values given do not influence the controller and are available for Bus interfaces,
display and analog outputs. Parameter values must not be changed.
REMARK
Examples on how to calculate the Ohm value of load resistors
Example 1 Thyro-P 1P400-110 H
• the power controller is Thyro-P 1P 400-110H with 110A type current
• the transformer has a transformation ratio of tr = 100:1
The currents of transformer are at nominal current of Thyro-P
• Primary current I
rms primary
= 110 A.
• Secondary current I
rms secondary
= 1.10 A.
The load resistor has to be dimensioned so that the voltage at load resistor is approx. 1V
eff
(0.9 -
1.1) at nominal current.
1 V
rms
1 V
rms
R
burden
= ——————— e.g. R
burden
= ——————— = 0,909 Ω
I
secondary (of transformer)
1,10 A
It would be ideal to use a load resistor of 0,909 Ω. If a resistor is not available with this value, it is
possible to use a similar resistor. Minimum and maximum value of used resistor are:
0.9 V
rms
0.9 V
rms
R
burden
min
= ——————— e.g. R
burden min
= ——————— = 0,818 Ω
I
secondary (of transformer)
1.10 A
1.1 V
rms
1.1 V
rms
R
burden max
= ——————— e.g. R
burden max
= ——————— = 1 Ω
I
secondary (of transformer)
1.10 A
After selecting a resistor, which value must be between 0,818 Ω and 1 Ω, the value has to be ente-
red with Thyro-Tool Family or LBA-2 in parameter U_Load resistor.