Internal Connection Diagram - Mitsubishi Electric MELPRO-A Series Instruction Manual

2. RUN display (Self-monitoring function)
This relay monitors
circuit, and program data at all time. The RUN LED
(green) lights up in the normal condition.
In the abnormal condition, the RUN LED goes out and
the error message Ｅ ｒ ｒ
numerical display LED, with the output contact
locked.
Since power supply is derived from CT secondary
current, the RUN LED lights up when the current input
exceeds approx. 1.5A.
3. Numerical display function
By switching the position of the indicator select
switch, following items can be displayed on the
numerical display LED.
①Current measurement
The display shows the input current value of
larger one among two phases. The display range is
from 2.0A to 30A.
(If input current is less than 2.0A, the display
goes out. If input current is more than 30A, the
error message Ｏ.Ｆ. is displayed.)
②Time lapse (including pickup display)
The pickup and time lapse of time-lag element is
displayed with the number from ０ to １０ .
Pickup: When input current exceeds setting value
of time-lag element, ０ is displayed.
Time lapse: The number from １
displayed according to a lapse of time
of time-lag element. The output contact
operates once １０ is displayed.
③Setting value
It displays the setting condition of the relay
including time-lag current, dial, instantaneous

Internal connection diagram

※ RD-type has shorting bar.
C1R Time-lag element
Instantaneous
I
R
element
C2R
C1T
Time-lag element
I Instantaneous
T
element
C2T
Power supply
Continuous
monitoring
Power circuit
monitoring
a）MOC-A3V-R、MOC-A3V-RD
control voltage, electric
is displayed on the
to １ ０
R-phase operation indicator
Instantaneous operation
indicator
T-phase operation indicator
RUN indicator
X0
X0 For alarm
X1 For trip
X1
Fig. 1-3 Internal connection diagram
current, number of step, sensitivity, operation
characteristic, and frequency.
4.
Fault record function
①Display of fault records
When a fault occurs, the relay outputs the
operating signal, and at the same time the current
value of larger one among two phases is recorded.
The relay can save the newest single phenomenon.
The record is saved in the non-volatile memory,
therefore the record can be read again after
shutting the power off.
Note that the fault record may not be saved if the
input current is turned off soon after the relay
operation.
②Clearing of fault records
Set indicator select switch to "CLEAR FAULT REC."
and hold for 5s or more, then Ｏ.Ｋ. is displayed
and all of the fault record are cleared.
5. Display function of setting change
When a setting is changed, the setting value after
changing is displayed for approx. 3s preferentially.
6. Detection function of frequency difference
If there is a difference between setting frequency
and injected frequency, the alert message Ｆ.Ｅ.
is displayed.
The detection is executed one second after the
is relay is activated or the frequency setting is
changed.
If the alert message Ｆ.Ｅ. is displayed, please
check the frequency setting switch.
C1R
Time-lag element
I X1
R
For trip
C2T2R
T1R
C1T
Time-lag element
I X1
T
a1
For trip
For alarm
C2T2T
a2
T1T
T1
For trip
T2
14
R-phase operation indicator
Instantaneous
Instantaneous operation
element
indicator
T-phase operation indicator
RUN indicator
X0
For alarm
Instantaneous
element
For trip
X1
Power supply
Continuous
monitoring
Power circuit
monitoring
b）MOC-A3T-R
X0
a1
For alarm
a2
JEP0-IL9553