<s>
IEC/IEEE	B-Protocol
61850-9-3	I-Protocol
(	O
Power	B-Protocol
Utility	I-Protocol
Profile	I-Protocol
)	O
or	O
PUP	O
is	O
an	O
international	O
standard	O
for	O
precise	O
time	O
distribution	O
and	O
clock	O
synchronization	O
in	O
electrical	O
grids	O
with	O
an	O
accuracy	O
of	O
1	O
μs	O
.	O
</s>
<s>
IEC/IEEE	B-Protocol
61850-9-3	I-Protocol
is	O
a	O
profile	O
(	O
subset	O
)	O
of	O
IEEE	O
Std	O
1588	O
Precision	B-Protocol
Time	I-Protocol
Protocol	I-Protocol
(	O
PTP	O
)	O
when	O
clocks	O
are	O
singly	O
attached	O
.	O
</s>
<s>
IEC/IEEE	B-Protocol
61850-9-3	I-Protocol
provides	O
seamless	O
fault	O
tolerance	O
by	O
attaching	O
clocks	O
to	O
duplicated	O
networks	O
paths	O
and	O
by	O
support	O
of	O
simultaneously	O
active	O
redundant	O
master	O
clocks	O
.	O
</s>
<s>
IEC/IEEE	B-Protocol
61850-9-3	I-Protocol
uses	O
the	O
following	O
IEEE	O
Std	O
1588	O
options	O
:	O
</s>
<s>
IEC/IEEE	B-Protocol
61850-9-3	I-Protocol
aims	O
at	O
an	O
accuracy	O
of	O
better	O
than	O
1	O
μs	O
after	O
crossing	O
15	O
bridges	O
with	O
transparent	O
clocks	O
.	O
</s>
<s>
IEC	O
TR	O
61850-90-4	O
(	O
Network	O
engineering	O
guidelines	O
)	O
gives	O
advice	O
on	O
the	O
use	O
of	O
IEC/IEEE	B-Protocol
61850-9-3	I-Protocol
.	O
</s>
<s>
IEC/IEEE	B-Protocol
61850-9-3	I-Protocol
restricts	O
the	O
parameters	O
of	O
IEEE	O
Std	O
1588	O
to	O
the	O
following	O
values	O
:	O
</s>
<s>
All	O
clocks	O
can	O
be	O
doubly	O
attached	O
using	O
the	O
IEC	O
62439-3	O
protocol	O
(	O
PRP	O
"	O
Parallel	B-Protocol
Redundancy	I-Protocol
Protocol	I-Protocol
"	O
or	O
HSR	O
"	O
High-availability	B-Protocol
Seamless	I-Protocol
Redundancy	I-Protocol
"	O
)	O
.	O
</s>
<s>
Technical	O
responsibility	O
rests	O
with	O
IEC	O
SC65C	O
WG15	O
,	O
which	O
is	O
committed	O
to	O
keep	O
the	O
IEC	O
62439-3	O
profile	O
L2P2P	O
and	O
IEC/IEEE	B-Protocol
61850-9-3	I-Protocol
aligned	O
.	O
</s>
