Schweitzer Engineering Laboratories SEL-351-5, Инструкция по эксплуатации

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4.54
SEL-351-5, -6, -7 Relay Instruction Manual
Date Code 20070117
Loss-of-Potential, Load Encroachment, and Directional Element Logic
Directional Control Settings
the same as the calculation for the VSCONN = VS example shown previously,
which converts the primary zero-sequence voltage value into a secondary
value on the
VA
,
VB
,
VC
input terminal base.
Using the example quantities from the VSCONN = VS subsection:
Note that the primary voltage is divided by the PTR setting, not the PTRS
setting.
Similarly, the derivation of the 32WFP and 32WRP settings, if they are known
in primary Watts, follows the same formula as before:
However, if the desired voltage pickup for the Wattmetric element is known in
terms of
VS channel volts (secondary), then the setting value must be scaled by
PTRS/PTR prior to entry. This pre-scaling makes the 59RES setting match the
scaling the relay does when it internally converts the
VS
channel value to the
VA, VB, VC voltage base.
For our example system, the desired 3V
0
pickup in terms of the voltage
applied to channel
VS
is:
The example 3V
0
pickup value in terms of the voltage applied to channel VS
is:
The 59RES setting is determined as follows:
As expected, this is the same value as before.
Similarly, if the desired Wattmetric pickup for the Wattmetric element is
known in terms of
VS channel volts (secondary) and IN channel current
(secondary), then the setting value must be scaled by PTRS/PTR prior to
entry. This pre-scaling makes the 32WFP and 32WRP settings match the
scaling the relay does when it converts the
VS value into the VA, VB, VC
voltage base.
For our example system, the desired Wattmetric pickup in terms of the voltage
applied to channel
VS
and the current applied to channel
IN
is:
59RES
V primary
PTR
------------------------
400 V primary
60
----------------------------------- 6.67 V secondary = = =
32WFP
W primary
PTR CTRN •
-----------------------------------
24000 W primary
60 10 •
------------------------------------------ 40.000 W secondary = = =
32WRP
W primary
PTR CTRN •
-----------------------------------
10000 W primary
60 10 •
------------------------------------------ 16.667 W secondary = = =
Voltage value (VS channel base)
V primary
PTRS
------------------------ =
Voltage value (VS channel base)
400 V primary
96
----------------------------------- 4.167 V secondary = =
59RES V secondary (VS base)
PTRS
PTR
---------------
• =
4.167
96
60
------ 6.67 V secondary = • =