Application Example; Power Measurement At A Machine - Beckhoff SCT Series Documentation

4

Application example

4.1

Power measurement at a machine

WARNING: Risk of electric shock!
Bring the Bus Terminal system into a safe, voltage-free state before starting mounting, disassembly or
wiring of the Bus Terminals!
Attention! Risk of device damage!
Avoid confusing the current and voltage circuit during connection, since the direct connection of mains volt-
age to the terminal points for the current transformers (typical input resistance 100 mΩ) would destroy the
power measurement terminal!
EL3443
• The voltage is measured via connections L1, L2, L3 and N.
• The current is measured via three current transformers (e.g. from the Beckhoff SCT series) and the
connections I , I , I
L1 L2
Fig. 55: EL3443, power measurement at a machine
**) PE as star point for 3-phase systems without neutral line
Depending on the current transformers used, PE must be connected as star point in 3-phase sys-
tems without neutral line as shown in Fig. "EL3443, power measurement at a machine ".
Observe the regulations of the manufacturer of the current transformers!
Negative power values
If negative power values are measured on a circuit, please check whether the associated current
transformer circuit is connected correctly.
EL3453
• The voltage is measured via connections L1, L2, L3 and N.
SCTxxxx
WARNING
and I (star point of the current transformers).
L3 N
Version: 1.1
NOTE
Application example
75