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Application examples

EL34xx260 Version: 1.5

7.1 Power measurement on motor with 2 or 3 current

transformers

WARNING

WARNING: Risk of electric shock!

If you do not connect terminal point N with the neutral conductor of your mains supply, you have to earth

terminal point N, in order to avoid dangerous overvoltages in the event of a fault with a current transformer!

NOTE

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 220mΩ) would destroy the

power measurement terminal!

EL3443

• The voltage is measured via the connections L1, L2 and L3.

• The current is measured with two current transformers [}29] via the connections I

and I

• The sum of all currents in the 3-phase mains network is 0. The value in circuit I

can be obtained

accordingly by wiring the EL3443.

Fig.161: EL3443, Power measurement with 2 current transformers on a motor

In the circuit shown above (Fig. EL3443, power measurement with 2 current transformers on a motor),

ensure that the three-phase system is either earth-free or has an earthed star point. Alternatively a

transformer can be included in a Yy0 circuit.

EL3453

• The voltage is measured via the connections L1, L2 and L3.

• The current is measured with three current transformers [}29] via the connections I

, I

.and I

Beckhoff EL34 Series User Manual

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