The thermal memory is a means to simulate temperature rise
and cooling caused by changes in the
Ň
ow of current in the
conductors.
These changes may be caused by:
-- Repe
ƟƟ
ve motor star
Ɵ
ng;
-- Loads
Ň
uctua
Ɵ
ng near the protec
Ɵ
on se
ƫ
ngs;
-- Repeated circuit breaker closing on a fault.
Even very short overloads or short circuits can produce a certain
temperature rise. During normal opera
Ɵ
ons these event are
tracked and stored in thermal memory resul
Ɵ
ng in a reduc
Ɵ
on in
the total circuit breaker tripping
Ɵ
me.
If the Circuit Breaker has tripped on a over current event the
thermal e
ī
ects of the current previously running in the circuit
will be taken into account. (remembered). This can result in a
preven
Ɵ
on of breaker re-closure onto a circuit running in 'Hot
condi
Ɵ
ons' or cause the men
Ɵ
oned reduc
Ɵ
on in the total
tripping
Ɵ
me a
Ō
er re-closure.
The trip unit tracks these occurrences across a
Ɵ
me frame of 12 minutes.
Four pole ME09 circuit breakers are equipped with a neutral
pole located on the le
Ō
, when viewed from the breaker front.
The Mpro trip unit allows the neutral pole to be op
Ɵ
oned with
or without a full set of protec
Ɵ
on devices. When neutral
protec
Ɵ
on is chosen the LT (overload) protec
Ɵ
on device in the
neutral pole can be set at on of three di
ī
erent values. Choosing
neutral protec
Ɵ
on and the value thereof depends on the
network and installa
Ɵ
on con
Į
gura
Ɵ
on.
The following op
Ɵ
ons are available:
-- Neutral unprotected (0%)
-- Neutral protected and the LT protec
Ɵ
on set at one of three values.
-- 50% Half Neutral protec
Ɵ
on
-- 63% Neutral Protec
Ɵ
on
-- 100% Full Neutral protec
Ɵ
on)
Se
ƫ
ng the LT device in the Neutral pole in
Ň
uences other
installed protec
Ɵ
on devices (if present) as indicated in table
2.11:
2.2.7
ඤऻᅬ
2.2.8
ዐႠԍࢺ
2.2.7 Thermal Memory
2.2.8 Neutral Protec
Ɵ
on
Table 2.11
ඤऻᅬఇెᆯڞ၍ዐۉୁՎࣅܸڞዂ࿒ืईૐඐڦᅃዖ
ݛ݆ă
ۉୁՎࣅీᆯᅜူᇱᅺሰׯǖ
--
ዘްഔۯۉऐǗ
--
ԍࢺยዃৎڦࢁհۯǗ
--
ୟഗᅺࠤቱܸዘްԿࢇă
न๑้क़܌ڦࡗሜई܌ୟᄺࣷሰׯᅃۨڦ࿒ืăኟሏ
ႜक़Ljܔኄၵ๚ॲႜ߶ጷժॽഄ٪ئሞඤऻᅬዐLj๑
ጺڦୟഗཌቄ้क़३ณă
සࡕୟഗᆯᇀࡗۉୁ๚ॲܸཌቄLjႴ୯ኮമۉୟዐۉ
ୁڦඤၳᆌDŽऻᅬDžăኄᄣᅜݞኹୟഗሞሏႜሞ
“
ඤጒ
”
ူڦۉୟฉምْԿࢇLj३ณምْԿࢇࢫڦጺཌቄ้
क़ă
ۉጱྃ੩ഗሞ
12
ݴዓڦ၌ా߶ጷኄၵ๚ॲă
5!ट!NF1:!ୟഗದᆶዐႠटLjٗୟഗኟ௬࠵ੂ้Ljዐ
Ⴀट࿋ᇀፑ֨ă!Nqsp!ۉጱྃ੩ഗሎႹሞದᆶईுᆶඇ༫
ԍࢺጎዃڦཉॲူስದԢዐႠटăስዐႠԍࢺ้Ljዐ
Ⴀटాڦ! MUDŽࡗሜDžԍࢺጎዃยዃྺ! 4! ߲փཞኵኮ
ᅃăስዐႠԍࢺLjยዃኵൽਦᇀྪஏࢅҾጎದዃă
ᅜူၜᆩǖ
..!࿄ԍࢺڦዐႠट!)1&*
..!ዐႠԍࢺLjMU!ԍࢺยዃྺෙ߲ኵኮᅃă
..!61&!ӷዐႠԍࢺ
..!74&!ዐႠԍࢺ
..!211&!ྜඇዐႠԍࢺ
ዐႠटాڦ! MU! ጎዃยዃࣷᆖၚҾጎڦഄጎዃDŽස٪
ሞDžLjස!3/22!๖ǖ
2.2-08
NF1:ဣଚگუഘୟഗ
֡ፕ
၂๖ೡఇ๕
൸၍
स٪ഗ
Ҿጎ
থ၍
ୟഗ
ॲ
֪
BREAKER
LOCKS
ACCESSORIES
TESTS
APPENDIX
ᆅჾ
ۉጱྃ੩ഗ
INTRO
TRIP UNIT
ዐႠยዃ
ԍࢺጎዃ
ዐႠटాڦጎዃยዃ
LT
ST
I
Gf sum
LT
ST
I
Gf sum
LT
ST
I
Gf sum
LT
ST
I
Gf su
100%
100%
100%
100%
63 %
63%
63%
63%
50 %
50%
50%
50%
0%
0%
0%
0%
100 %
63 %
50 %
0 %
Neutral se
ƫ
ng
Protec
Ɵ
on Device
Device se
ƫ
ng in Neutral pole
LT
ST
I
Gf sum
LT
ST
I
Gf sum
LT
ST
I
Gf sum
LT
ST
I
Gf su
100%
100%
100%
100%
63 %
63%
63%
63%
50 %
50%
50%
50%
0%
0%
0%
0%
100 %
63 %
50 %
0 %
!
2.11
ຫ
ׂ