I.L. 40-385.5
7-1
7.1
GENERAL DESCRIPTION
The operator panel (Figure 4) provides an integral
convenient means of checking or changing settings,
and of checking relay-unit operations after a fault.
Fault location, trip type, phase units which operated,
and breakers which tripped are available for most
recent 2 faults by using pushbuttons to step through
the information. Targets from the last 16 faults are
stored even if the relay is deenergized and are avail-
able through remote communication only.
The operator panel contains 7 LEDs as follows:
(1)
Relay in service — When this LED illuminates
the MDAR (REL-300) relay is in service, there
is dc power to the relay and the relay has
passed the self-check and self-test. The LED
will turned OFF if the relay has any internal fail-
ure shown in the “Test” mode, and the relay trip
output will be blocked.
(2)
Settings — For read or change settings.
(3)
Monitoring — The display shows three-phase
voltage, current and angle.
(4)
Last Fault — When flashing, indicates new fault
information available.
(5)
Previous Fault — When last fault LED flashes
twice per minute, indicates information for the
fault proceeding the last fault.
(6)
Value Accepted — When the “Settings” LED is
also ON, the “Value Accepted” LED flashes
only once, to indicate that a new setting value
is accepted; when the “Test” LED is also ON,
the output contacts can be tested.
(7)
Test — Use for verifying self-check and perform
functional test.
The operator is notified that targets are avail-
able by flashing LED's on the panel, plus an
output relay contact provided to operate an
external annunciator.
The operator can also look at non-fault voltage, cur-
rent and phase angle on the display. Settings can be
easily checked as well. The display will be blocked
momentarily, every minute, for the purpose of self-
check; this will not affect the relay protection function.
There are five test points on the MDAR (REL-300)
relay front panel to measure power supply voltage.
The test points provide measurement of the -24, +5, -
12 and +12 Vdc voltages.
The serial port on the rear panel (Figure 2) is pro-
vided for remote transmission of target data, remote
setting and optional oscillographic data. It also can
be used for future networking, data communications.
7.2
FRONT PANEL INTERFACE OPERATION
The operator interface consists of a vacuum display
with four alphanumeric characters for the function
field and four alphanumeric characters for the value
field, seven pushbuttons, seven LED's, and five test
points. All relay functions can be locally set, moni-
tored, and tested from this front panel interface (Fig-
ure 4).
7.2.1
Display Selection
The display selection pushbutton controls the type of
information displayed. The options include settings,
metered values, two sets of fault data, and test mode.
One of the five display modes is always selected and
is indicated by an illuminated LED. Depressing the
“DISPLAY SELECT” pushbutton changes the display
information to the next selection.
7.2.2
Entering Settings
The operation of the MDAR (REL-300) relay is con-
trolled through the settings. To access the settings,
the “DISPLAY SELECT” pushbutton should be
depressed until the “SETTINGS” LED is illuminated.
The RAISE and LOWER FUNCTION pushbuttons
are depressed to scroll through the settings. The
RAISE and LOWER VALUE pushbuttons are
depressed to change the settings. When the desired
value appears on the VALUE display, depressing the
“ENTER” pushbutton causes the displayed value to
be entered for the displayed function. The “VALUE
ACCEPTED” LED flashes once to indicate that the
value has been successfully entered into the system.
7.2.3
Displaying Monitoring Data
All three-phase currents, voltages and phase angles
are available for on-line display during normal opera-
tion. Conditions such as out-of-step blocking, loss-of-
Section 7. OPERATOR INTERFACE
