Sel 411L - Page 677

P.9.31
Date Code 20151029 Protection Manual SEL-411L Relay
Monitoring and Metering
Metering
Maximum/Minimum Metering Accuracy
The accuracy of the maximum/minimum metering quantities is the same as
the equivalent instantaneous metering accuracies listed in Table 9.17 and
Table 9.16. The relay maximum/minimum metering values are a true
reflection of the extremes that occur in the power system.
View or Reset Maximum/Minimum Metering Information
The relay shows time stamped maximum/minimum quantities when you use a
communications port or
ACSELERATOR QuickSet to view these quantities. In
addition, you can read the maximum/minimum quantities on the relay
front-panel LCD screen.
To reset the maximum/minimum values, use the MET RM command from a
communications terminal, or use the RESET button in the
ACSELERATOR
QuickSet HMI > Meter and Control > Maximum/Minimum window, or
answer
Y and press ENT at the Maximum/Minimum submenu reset prompt on the
front-panel LCD screen. You can also reset maximum/minimum metering
with Global settings RSTMML, RSTMMB1, and RSTMMB2 (for line,
Circuit Breaker 1, and Circuit Breaker 2) when EDRSTC (Data Reset Control)
is Y.
Maximum/Minimum Metering Updating and Storage
The relay updates maximum/minimum values once per power system cycle.
The relay stores maximum/minimum values and the corresponding dates and
times to nonvolatile storage once per day. If greater than a previously stored
maximum or less than a previously stored minimum, the new value overwrites
the previous value. Should the relay lose control power, it will restore the
maximum/minimum information saved at 23:50 hours on the previous day.
The relay updates maximum/minimum values under the following conditions:
➤ DFAULT is deasserted (equals logical 0)
➤ The metering value is greater than the previous maximum, or
less than the previous minimum, for 2 cycles
➤ Voltage input is greater than 13 V secondary
➤ Current input is greater than 0.05 • I
NOM
(in secondary amps)
Megawatt and megavar maximum/minimum values are subject to the above
voltage thresholds, current thresholds, and conditions.
FAULT SELOGIC Control Equation
The relay suspends updating maximum/minimum metering when SELOGIC
control equation FAULT asserts to logical 1. If there is a fault, the elements
programmed in FAULT pick up and assert Relay Word bit DFAULT (Delayed
FAULT Suspend). This Relay Word bit remains asserted for one minute after
SEL
OGIC control equation FAULT deasserts. While DFAULT is asserted, the
relay does not record maximum/minimum data.
Three-phase reactive power 3Q
1
Three-phase true apparent power 3U
rms
a
Sequence components are maximum values only.
Table 9.17 Maximum/Minimum Metering Quantities—Voltages, Currents,
Frequency, and Powers (Sheet 2 of 2)
Metered Quantity Symbol