Technical data

1MRS751108-MUM
REX 521
23
Protection Relay
Technical Reference Manual, General
5.1.4.1. Power supply versions
There are two basic versions of power supply modules available for REX 521
protection relays: type PS_87H and type PS_87L.
The input voltage range of the power supply module is marked on the front panel of
the REX 521 unit. The power supply version is specified by a letter in the order
number of the protection relay (refer to section “Ordering information” on page 61).
The voltage range of the digital inputs is tied to the selected power supply. If a power
supply version with the higher rated input voltage is selected, the protection relays
will be delivered with digital inputs that also have the higher rated input voltage. The
digital input, DI9, on the CPU module has also lower rated input voltage.
The auxiliary voltages of power supply modules and the corresponding rated input
voltages of digital inputs are:
For further technical data of the power supply, see Table 5.2.1-2 on page 48.
5.1.4.2. Low auxiliary voltage indication
The relay is provided with a low auxiliary voltage indication feature. The power
supply module issues an internal alarm signal when a drop in the power supply
voltage is detected. The alarm signal is activated if the power supply voltage falls
about 10% below the lowest rated DC input voltage of the power supply module, see
the following table:
The indication of a low auxiliary voltage (ACFail) can be seen as an event via serial
communication.
5.1.5. Overtemperature indication
The REX protection relay includes an internal temperature supervision function.
The CPU module issues an internal alarm signal when overtemperature has been
detected inside the relay enclosure. The alarm signal will be activated once the
temperature inside the relay enclosure increases approximately to +78
o
C. The
overtemperature indication can be seen on the HMI or as an event via serial
communication. The relay will go to the IRF (internal relay fault) state. See
Table 5.1.11.2-1, “Fault indications,” on page 35.
Power supply module
Rated input voltage
of power supply
Rated input voltage
of digital inputs
PS_87H 110/120/220/240 V AC
or 110/125/220 V DC
DI1...DI8: 110/125/220 V DC
DI9: 24/48/60/110/125/220 V DC
PS_87L 24/48/60 V DC DI1...DI9: 24/48/60/110/125/220 V DC
Rated input voltage Low indication level
PS_87H
• Rated input voltage 110/125/ 220 V DC 99 V DC
• Rated input voltage 110/120/220/ 240 V AC 88 V AC
PS_87L
• Rated input voltage 24/48/60 V DC 21.6 V DC