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MPCB CLASS

Created by: jeet2907 at: 7/16/2013 11:44 AM (9 Replies)

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7/16/2013 11:44 AM	Rate (0)
jeet2907 Posts: 235 Rating: (52)	DEAR FRENZ What is the mean of CLASS in mpcb and diffrence between various classes?
jeet2907 Posts: 235 Rating: (52)
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7/16/2013 12:08 PM	Rate (1)
Valli Posts: 262 Rating: (45)	Hi, As per IEC 60947 overload characteristics of any protective device indicates the maximum tripping time within which MPCB/ overload relay must trip cold @ 6-7 times of the Set Current. That means if the motor's starting time is within 10 sec.. select MPCB with Class10 and if it is more than 10 then use Class 20. Since, MPCB's are used primirly within 100A of motor current you may not find applications where in motors are switching ON above 20sec. For any other class like 30 etc ( cursher etc application)we have 3RB relays which has selectable class 5....40 and MPCB only for short circuit protection.
Valli Posts: 262 Rating: (45)
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7/16/2013 12:53 PM	Rate (0)
@nkur Posts: 202 Rating: (16)	Valli Hi, As per IEC 60947 overload characteristics of any protective device indicates the maximum tripping time within which MPCB/ overload relay must trip cold @ 6-7 times of the Set Current. That means if the motor's starting time is within 10 sec.. select MPCB with Class10 and if it is more than 10 then use Class 20. Since, MPCB's are used primirly within 100A of motor current you may not find applications where in motors are switching ON above 20sec. For any other class like 30 etc ( cursher etc application)we have 3RB relays which has selectable class 5....40 and MPCB only for short circuit protection. HI MPCB/ overload relay must trip cold WHAT IT ACTUALLY MEANS?
@nkur Posts: 202 Rating: (16)
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7/16/2013 12:59 PM	Rate (0)
Valli Posts: 262 Rating: (45)	Hi, Selection of MPCB's class should be based on cold start time of the motor... i.e. motor has 2 types of start hot and cold. Hence, i suggested that starting current is around7.2times of rated current ( i.e. cold start) Genrally siemens 1LG6 motors are manufactured for 2Hot and 3cold start.
Valli Posts: 262 Rating: (45)
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This contribution was helpful to 1 thankful Users @nkur

7/17/2013 1:02 PM	Rate (0)
@nkur Posts: 202 Rating: (16)	Valli Hi, Selection of MPCB's class should be based on cold start time of the motor... i.e. motor has 2 types of start hot and cold. Hence, i suggested that starting current is around7.2times of rated current ( i.e. cold start) Genrally siemens 1LG6 motors are manufactured for 2Hot and 3cold start. Hi There Can you please futher elaborate on COLD & HOT start??
@nkur Posts: 202 Rating: (16)
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5/21/2014 7:06 PM	Rate (0)
@nkur Posts: 202 Rating: (16)	Valli Hi, Selection of MPCB's class should be based on cold start time of the motor... i.e. motor has 2 types of start hot and cold. Hence, i suggested that starting current is around7.2times of rated current ( i.e. cold start) Genrally siemens 1LG6 motors are manufactured for 2Hot and 3cold start. Hi There You have clealy explained what is cold start but what about the HOT start does it has an perticlar current value WRT the rated current?
@nkur Posts: 202 Rating: (16)
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5/21/2014 7:08 PM
@nkur Posts: 202 Rating: (16)	jeet2907 DEAR FRENZ What is the mean of CLASS in mpcb and diffrence between various classes? Also could anyone explain me in which of the 2 types of MPCB i.e Standard & relay function do i need to consider OLR???
@nkur Posts: 202 Rating: (16)
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5/21/2014 7:09 PM
@nkur Posts: 202 Rating: (16)	jeet2907 DEAR FRENZ What is the mean of CLASS in mpcb and diffrence between various classes? Also what is the use of ALARM contacts in the MPCB does it provides protection against overload???
@nkur Posts: 202 Rating: (16)
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5/24/2014 7:08 AM	Rate (1)
jeet2907 Posts: 235 Rating: (52)	@nkur jeet2907 DEAR FRENZ What is the mean of CLASS in mpcb and diffrence between various classes? Also what is the use of ALARM contacts in the MPCB does it provides protection against overload??? Dear @nkur Fist of know that their are three types of MPCB are availabe 1)Standard Release 2)Magnetic release 3)Relay function As per above classification they provide diffrent protection 1)Standard Release MPCB provide protection for trips on SC and also on OL 2) Magnetic release MPCB provide protection for trips on SC 3) Relay function MPCB provide protection for trips on SC and opens contactor on OL Now your Question to use of ALARM contacts in the MPCB does it provides protection against overload??? Answer is YES if OL protection is available in MPCB then you can use alarm contact to provide protection for the same and this OL protection available only in two type of MPCB which is expaine above.
jeet2907 Posts: 235 Rating: (52)
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5/26/2014 11:34 AM	Rate (0)
Chetan2490 Advanced Member Joined: 5/12/2014 Last visit: 9/9/2020 Posts: 149 Rating: (16)	jeet2907 DEAR FRENZ What is the mean of CLASS in mpcb and diffrence between various classes? Dear , The MPCBs class : 1.MPCB with standard release 2.MPCB with relay function 3.MPCB with “MAG only” release 4.MPCB with Class 20 release 5.MPCB for Transformer protection

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