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Voltage Monitoring (RPW/ERWM)
20
They are electronic devices intended to monitor three-phase systems and interrupt the
process operation whenever a failure occurs. Designed according to international standards,
they are available in 22.5 mm wide housings and can be mounted on DIN rails 35 mm or
fixed with screws (PLMP accessory required), being a compact and safe solution.
RPW-FF - Phase Loss Function
It is intended to protect three-phase systems against the loss of one phase (without neutral). For monitoring the neutral, a
bridge must be provided between terminals A and B; thus the RPW-FF will monitor the phase loss and also the neutral
voltage (terminal N).
Installation
It is directly connected to the three
phases (terminals L1, L2 and L3) of the
power grid to be monitored (connect
the neutral if applicable).
Note: The RPW-FF protects against ghost phase - In the monitoring of an electric motor, the phase loss makes the remaining phases induce a ghost phase on
the winding coil of the respective phase, raising the current of the other two phase and overheating the motor. The winding with induced voltage works as
a voltage generator (ghost phase).
Note: for application in generator sets, frequency inverters with 12-pulse or regenerative rectifiers, electronic power controllers (dimmers or the like) or where a high level
of harmonic currents may be present (above the recommendation of IEEE519), we recommend the ERWM relay.
Selection
Specification
Wiring Diagram
RPW - FF - D70
Supply voltage (L1-L3-L3) 50/60 Hz Reference
220-240 V ac RPW-FF-D66
380-415 V ac RPW-FF-D70
440-480 V ac RPW-FF-D74
L1 15 L2
16 18 L3
RPW FF
A B N
Neutral
selection
L1 L2 L3
A B N
16 18
15
t
The RPW protective relay
has LEDs for state indication,
as shown on the right:
Certifcations
Power supply selection
D66 = 220-240 V ac 50/60 Hz
D70 = 380-415 V ac 50/60 Hz
D74 = 440-480 V ac 50/60 Hz
Phase loss functionWEG Protective / Monitoring
VOLTAGE
MONITORS
Operation
The output relay switches the contacts to the operation position (closing terminals
15-18), and the red LED (relay) and green LED (supply voltage) will switch on.
Adjust the sensitivity of the line voltage.
If one of the phases drops below the percentage limit set on the dials, the coil
output contacts will be de-energized, opening contacts 15-18, and the red LED
will turn OFF.
Energized output
Energized relay
LED
OFF
LED
ON
LED
ON
LED
OFF
16 18
15-18
15-16
N
L3
L2
L1
V
16 18
16 18
16 18
15
15
15
15