Micom P721, Technical Manual

Page: 43 / 334

User Guide P72x/EN FT/C21
MiCOM P721/P723 Page 3/38
1. PRESENTATION OF MiCOM P721 AND P723 PROTECTIONS
MiCOM P721 and P723 are fully numerical relays designed to perform electrical protection
and control functions.
The following section describes the MiCOM P72x range and the main differences between
the different models.
MiCOM relays are powered either from a DC (2 voltage ranges) or an AC auxiliary power
supply.
Using the front panel, the user can easily navigate through the menu and access data,
change settings, read measurements, etc.
Eight LEDs situated in the front panel help the user to quickly know the status of the relay
and the presence of alarms. Alarms that have been detected are stored and can be
displayed on the back-lit LCD.
Any short time voltage interruption (<50ms) is filtered and regulated through the auxiliary
power supply.
Regarding current inputs, MiCOM P721 has one earth current input available for 1A and 5A
rated CTs.
MiCOM P723 has 3 phase and 1 earth current inputs available for 1 and 5 Amps rated CTs.
On each one of these relays, it is possible to combine 1 and 5 Amp current inputs together (i-
e a mix between 1A for earth fault and 5A for phase connections).
MiCOM P721 and P723 relays continuously measure phase and earth currents and take into
account the true RMS current value up to 10th harmonic (at 50 Hz).
Output relays are freely configurable and can be activated by any of the control or protection
functions available in the relay. Logic inputs can also be assigned to various control
functions.
On their rear terminals MiCOM P721 and P723 have a standard RS485 port available. When
ordering, the user can choose between the following communication protocols: ModBus
RTU, IEC 60870-5-103 or DNP3.0.
Using RS485 communication channel, all stored information (measurements, alarms, and
parameters) can be read and settings can be modified when the chosen protocol allows it.
Reading and modification of this data can be carried out on site with a standard PC loaded
with Schneider Electric setting software.
Thanks to its RS485 based communication, MiCOM P721 and P723 relays can be
connected directly to a digital control system. All the available data can then be gathered by
a substation control system and be processed either locally or remotely.