2. Description of Operation
The MK2000 relay provides three independent phase overcurrent elements
and one non-directional earth-fault element. All these elements are connected
to the current transformers of the feeder to be protected.
2.1 Phase Overcurrent Protection
When the phase current exceeds the low-set I> setting value, the overcurrent
low-set element starts and delivers a start signal to the display panel and a
group of pre-assigned relay outputs. After a delay time, determined by the
inverse time current characteristic curve selected and measured current, this
overcurrent element operates and delivers a trip signal to the display panel
and a group of relay outputs that are configured to link to the low-set phase
overcurrent tripping.
When the phase current exceeds the high-set I>> setting value, the
overcurrent high-set element starts and delivers a start signal to the display
panel and a group of pre-assigned relay outputs. After a pre-set time,
determined by t>>, this overcurrent element operates and delivers a trip
signal to the display panel and a group of relay outputs that are configured to
link to high-set phase overcurrent tripping.
2.2 Earth-Fault Protection
When the earth-fault current exceeds the low-set I
O
> setting value, the earth-
fault low-set element starts and delivers a start signal to the display panel
and a group of pre-assigned relay outputs. After a delay time, determined by
the inverse time current characteristic curve selected and measured current,
this earth-fault element operates and delivers a trip signal to the display
panel and a group of relay outputs that are configured to link to the low-set
earth-fault tripping.
When the earth-fault current exceeds the high-set I
O
>> setting value, the
earth-fault high-set element starts and delivers a start signal display panel
and a group of pre-assigned relay outputs. After a pre-set time, determined by
t
O
>>, this earth-fault element operates and delivers a trip signal to the display
panel and a group of relay outputs that are configured to link to high-set
earth-fault tripping.
MK2000
Page 3
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