Binary Inputs; Alarm And Tripping Inputs; Ac Rejection - Siemens 7SR12 Argus Manual

7SR11 & 7SR12 Applications Guide
1.2

Binary Inputs

Each Binary Input (BI) can be programmed to operate one or more of the relay functions, LEDs or output relays.
These could be used to bring such digital signals as Inhibits for protection elements, the trip circuit supervision
status, autoreclose control signals etc. into the Relay.
1.2.1

Alarm and Tripping Inputs

A common use of binary inputs is to provide indication of alarm or fault conditions e.g. transformer Buchholz Gas
or Buchholz Surge conditions. The Binary Inputs are mapped to LED(s), waveform storage trigger and binary
outputs. Note that transformer outputs which require high speed tripping, such as a Buchholz Surge, should be
wired to a binary input to provide LED indication and also have a parallel connection wired to directly trip the
circuit via a blocking diode, see figure. 1.2-1:
Buchholz Gas
Buchholz Surge
Wdg. Temp Alarm
Wdg. Temp Trip
Oil Temp Alarm
Oil Temp Trip
POWER
TRANSFORMER
Figure 1.2-2 Example of Transformer Alarm and Trip Wiring
1.2.2

AC Rejection

The default pick-up time delay of 20ms provides immunity to ac current for dc applications e.g. induced from cross
site wiring.
19V Binary inputs can be configured for intentional operation from a 100-120V ac power supply by setting pickup
and drop-off timers for each binary input. 0ms PU and 25ms DO. Binary inputs are not rated for use on 220-250V
AC. If wiring to AC operate binary inputs is required to have a total length of more than 10 metres, screened
twisted pair cable should be used.
Page 6 of 48
+
Blocking
Diodes
-
RELAY
+ve
BI n
-ve
+ve
BI n
-ve
+ve
BI n
-ve
+ve
BI n
-ve
+ve
BI n
-ve
+ve
BI n
-ve
TRIP CIRCUIT
©2017 Siemens Protection Devices Limited
BO n
BO n
BO n
BO n