Protection Against Shock Hazard Voltages - WAGO 750-494 Series Manual

74 Connect Devices
connected measuring instruments. FS shall be max. 10 for the 1 A module resp.
max. 5 for the 5 A module.
Note the max. continuous measuring current of 1 A resp. 5 A!
The max. continuous measuring current of the module is 1 A resp. 5 A. If the used
transformers allow greater secondary currents than 1 A resp. 5 A install additional
transformers with an appropriate transforming ratio!
7.3.2.4

Protection against Shock Hazard Voltages

No hazardous voltage is produced when the 3-phase power measurement module
is used as specified, with appropriate current transformers. Secondary voltage is
only a few Volts. Nevertheless, the following faults can result in high voltage
levels:
• Open current path for one or more transformers
• Disconnected/cut N conductor at the voltage measuring end of the 3-phase
power measurement module
• General insulation faults
Install protection against electric shock!
All wiring for the measurement system shall be equipped with protection against
shock hazard voltages along with the corresponding safety signs!
The 3-phase power measurement module permits a maximum voltage of 480 V
for normal operating conditions. The voltages at the voltage inputs shall not
exceed 480 V. For higher voltages use a transformer stage. This one however,
shall not produce a phase angle shift (Yy0)!
The 3-phase power measurement module is equipped with a protective impedance
of 1072 kΩ at the voltage measurement end. If the N conductor is not connected,
and only one of the three voltage measuring terminals is under power, a voltage of
230 VAC to ground is yielded in a 3-phase system with a phase-to-phase voltage
of 400 VAC. This voltage is also present at the current measuring end and can be
measured using a multimeter with 10 MΩ input resistance. This does not represent
an insulation fault.
WAGO-I/O-SYSTEM 750
750-494 3-Phase Power Measurement Module
Manual
Version 1.2.0