Boost Ratio; Priority Rules For Boosting - ABB ETL600 Instruction Manual

ETL600
the ETL600. Signals occupying all or part of the band between 300
to 2000 Hz where an NSD600 device is operating must be discon-
nectable, as this band must be kept free for transmission of the
NSD600 tripping signals.
Caution
•
The output signal path of a disconnectable port is disabled, if the
NSD600 teleprotection system is transmitting or receiving a
tripping signal. The output signal path is not affected, when an
external teleprotection system, like a NSD570/NSD70C is
transmitting or receiving a tripping signal.
•
The input and output signal paths of a non-disconnectable port
are not disabled during the transmission of tripping signals. The
signals entering the PLC terminal via such a port are called non-
disconnectable signals. The power of non-disconnectable signals
is not available for the teleprotection tripping signal.
5.2.16.2.

Boost Ratio

The ratio between the PE power of the boosted teleprotection signal
and the PE power of the unboosted signal is called Boost Ratio (BR)
and is normally expressed in decibels.
The boost ratio for any TPE device x is calculated by the system
according to the formula
=
BR
x
where
BR
S
∑
−
non disc
w
TPEx
In case of internal TPE, an upper limit to the boost ratio can be
specified by HMI600.
5.2.16.3.

Priority rules for boosting

Boosting of internal teleprotection devices NSD600 has priority over
boosting of external teleprotection devices. If several external
teleprotection devices are operated over the same ETL link, only one
of them will be boosted at the same time. The priority rules are
described below:
Boosting for NSD570/NSD70C in channel 1 is disabled while one or
both NSD600 devices are boosted.
Configuration and Set-up
1KHW001489-EN
For the APLC channels with NSD600 operation, all
signals which use the band between 300 to 2000 Hz
(or part of it) must be disconnectable.
⎛
∑
∗ ⎜ −
20 log S
⎝
−
non
is the boost ratio of TPE x,
x
is the S-value,
is the sum of the weights of the non-disconnectable
w
i
signals including the guard signals of the other TPEs,
.
is the weight of the guard signal of TPE x.
guard
⎞ (
⎟ − ∗
w 20 log w
i TPEx
⎠
disc .
November 2005
ABB Switzerland Ltd
)
(22)
,
guard
5-13