Operating Description - Mitsubishi Electric MELPRO-A Series Instruction Manual

Operating Description

1. Protection function
①The power supply can be derived from VT secondary.
②Set using condition switches according to your
using condition (frequency and output contact).
③ Zero-sequence voltage input is supplied from
secondary output of commercially available EVT
(compliance with JEC-1201).
④ Zero-sequence current input is supplied from
secondary output of MZT type ZCT combined with the
relay.
⑤If both zero-sequence current and zero-sequence
voltage is greater than or equal to the setting
value, and if the phase difference between them
is within the operating area, the operation timer
starts. The relay actuates the output contact and
operation indicator after a preset time of the
operation timer.
⑥ After the relay operation, if zero-sequence
current or zero-sequence voltage falls below the
setting value, or if the phase difference between
them is out of the operating area, the output
contact will be in the state set by the using
condition setting switch (auto-reset or self-hold).
The operation indicator keeps the operation status
(orange color). To reset the indicator, move the
reset lever up and down.
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.
3. Numerical display function
By switching the position of the indicator select
switch, following items can be displayed on the
numerical display LED.
①V voltage measurement
0
The display shows the value of zero-sequence
voltage. The display range is from 1.0% to 12.0%.
(If input voltage is less than 1.0%, the display
goes out. If input voltage is more than 12.0%, the
error message Ｏ.Ｆ. is displayed.)
Here, "100%" denotes complete single-phase fault,
that is, the rated input voltage of the relay
(110V/190V).
This function makes it possible to measure the
residual V voltage in sound condition.
0
②I current measurement
0
The display shows the value of zero-sequence
current. The display range is from 0.05A to 1.5A.
(If input current is less than 0.05A, the display
goes out. If input current is more than 1.5A, the
error message Ｏ.Ｆ. is displayed.)
control voltage, electric
is displayed on the
③Phase measurement
The display shows the phase of zero-sequence
current relative to the zero-sequence voltage.
The display range is 0°to 359°(lag).
④V , I pickup
0 0
When input zero-sequence voltage and zero-sequence
current exceeds setting value,
displayed.
(V pickup: Ｕ.－
0
When the indicator select switch is set to "PICKUP",
－ is displayed.
This function can be used for operation value tests.
⑤Setting value
It displays the setting condition of the relay
including V value, I
0
setting.
⑥Frequency setting
It displays the setting condition of frequency in
accordance with the setting switch of SW1.
⑦Output contact setting
It displays the setting condition of output contact
in accordance with the setting switch of SW2.
The setting is self-hold, the display shows
Ｈｏ..
The setting is auto-reset, the display shows
ＦＵ..
4. Fault record function
①Display of fault records
When a fault occurs, the relay outputs the
operating signal, and at the same time the input
values of zero-sequence voltage, zero-sequence
current and phase are recorded. When the indicator
select switch is set to the position of each fault
record, the records are displayed starting from
the latest record
approximately 2 second intervals. The relay can
save the newest five phenomena.
The records are saved in the non-volatile memory,
therefore the records can be read again after
shutting the power off.
Note that the fault record may not be saved if the
auxiliary power supply 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.
10
Ｕ . － Ｉ .
, I pickup: －Ｉ.)
0
value, and operating time
0
to the oldest
JEP0-IL9559
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