Table of Contents
Advertisement
66
3 zone impedance protection (Z(n)RW)
The input signal Z1RW-VTSZ, which is normally connected from the fuse failure su-
pervision function, is activated when ac voltage failure has been discovered in the sec-
ondary circuits between the voltage instrument transformers and the terminal. The
signal is deactivated when the fuse failure supervision function is disabled.
The binary signal Z1RW-BLKTR prevents the impedance function in zone 1 from
sending a tripping signal. Different external signals can be connected to the input for
this purpose.
The three logical output signals from the impedance function for zone 1 are:
•
Z1RW-START, which shows that underimpedance (Forward, Reverse or Non-di-
rectional) has been registered by zone 1.
•
Z1RW-NDST, which shows that underimpedance (non-directional) has been regis-
tered by zone 1.
•
Z1RW-TRIP, which gives the tripping order from the measuring element for zone
1.
The corresponding signals are also available in zone 3. Zone 2 (two phase version) has
three additional non-directional output start signals:
•
Phase-to-earth-fault phase L1 or L2.
•
Phase-to-phase fault
These signals may be used as phase selector information in the fault locator.
The output signals can be connected to the binary outputs and other functions in
REO 517.
&DOFXODWLRQV
The parameters for the impedance function are set via the local HMI or PST (Parameter
Setting Tool). Refer to the Technical reference manual for setting parameters and path
in local HMI.
The settings for the distance protection function must correspond to the parameters for
the protected line and also correspond with the selective plan for the network.
All settings are of the secondary value, which is why it is necessary to recalculate the
primary line impedance to the secondary side of the current and voltage transformers.
&KDSWHU
/LQH LPSHGDQFH
Advertisement
Table of Contents
