WAGO 750-495/040-00 Series Manual page 83

WAGO-I/O-SYSTEM 750 XTR
750-495/040-00x 3-Phase Power Measurement Module 690 V
Calculation of the measured values for cos phi
Electric Circuit
Number
Process value
PI scaling factor
Formula
Measured value for
cos phi
Calculation of the current-dependent measured values (current, power and
energy)
For the 750-495/040-000 and 750-495/040-001 versions, the current
transformer ratio (CTR) must be taken into account in the calculation of the
current-dependent variables.
Current transformers
Various current transformer designs are available on the market. Currents of 1 A,
5 A, 10 A, 5000 A are supported on the primary side and of 1 A or 5 A on the
secondary side.
For example, transformation ratios of 45:1 A (750-495/040-000) or 200:5 A
(750-495/040-001) are possible. These yield corresponding current transformer
ratios (CTRs) of 1:45 and 1:40.
The I/O module offers the option of setting a user scaling, either with WAGO-
I/O-CHECK or via register 32, bits 12 ... 15. If the corresponding bit is set to 0,
user scaling is disabled, and the transformation ratio of the current is 1:1. If the
bit is set to 1, user scaling is activated, and the transformation ratio of the current
transformer used is taken into account in the I/O module already.
Always enable user scaling and set CTR
To avoid unnecessary calculations outside the I/O module, always enable user
scaling and set the current transformer ratio in the I/O module.
Large measured values can also be represented in the process image on the
basis of 32-bit process values.
750-495/040-000,
750-495/040-002
0xFFFFFFB2 (−78)
0.01
Measured value = process value × PI scaling factor
−0.78
Process Image
750-495/040-001
0x00000059 (89)
0.01
0.89
Version 1.2.0
83
Manual