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5.22
SEL-421 Relay
Instruction Manual
Date Code 20171021
Protection Functions
Time-Error Calculation
Time-Error Command (TEC)
The
TEC
serial port command provides easy access to the time-error function.
TEC on page 14.54 in the SEL-400 Series Relays Instruction Manual
for
command access-level information.
Enter the
TEC
command to view the time-error status. A sample display is given
Enter the
TEC
command with a single numeric argument
n
(–30.000
n
30.000) to preload the TECORR value. This operation does not affect the TE
analog quantity until the SEL
OGIC
control equation LOADTE next asserts.
shows an example of the
TEC
n
command in use.
Global Settings
NFREQ
LOADTE
Load time-error correction factor (SEL
OGIC
control equation). A rising edge
will cause the relay to load the TECORR analog quantity into TE. LOADTE
has priority over STALLTE.
STALLTE
Stall time-error calculation (SEL
OGIC
control equation). A logical 1 will stall
(freeze) the time-error function. The TE value will not change when
STALLTE is asserted (unless LOADTE asserts).
Relay Word bit
FREQOK
Frequency measurement valid. If this Relay Word bit deasserts, the TE quan-
tity is frozen (see
).
OUTPUTS
Description
Analog Quantity
TE
Time-error estimate, in seconds. Positive numbers indicate that the ac clock
would be fast (ahead of the reference clock). Negative numbers indicate that
the ac clock would be slow (behind the reference clock).
Relay Word bit
PLDTE
Preload Time-Error value updated. This element asserts for approximately
1.5 cycles after TECORR is changed by the TEC command or by DNP3.
Table 5.18
Time-Error Calculation Inputs and Outputs (Sheet 2 of 2)
INPUTS
Description
=>
TEC <Enter>
Relay 1 Date: 11/02/2004 Time: 11:25:50.460
Station A Serial Number: 0000000000
Time Error Correction Preload Value
TECORR = 0.000 s
Relay Word Elements
LOADTE = 0, STALLTE = 0, FREQOK = 1
Accumulated Time Error
TE = -7.838 s
=>
Figure 5.15
Sample TEC Command Response
==>
TEC 2.25 <Enter>
Relay 1 Date: 11/02/2004 Time: 11:53:12.701
Station A Serial Number: 0000000000
Change TECORR to 2.250 s:
Are you sure (Y/N)?Y
<Enter>
Figure 5.16
Sample TEC
n
Command Response
Summary of Contents for SEL-421-4
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