To my understanding Icm stands for Short Circuit Making
Capacity.
According to standard IEC 947-2 or BS EN60947, etc.
It is equal to 2.2 x Icu, where Icu means Ultimate breaking
capacity.
Circuit breakers are designed with withstand short circuit
currents for a short period of time, defined as Icw for a
period of 1 second. This is designed to guarantee
selectivity of breakers and other devices providing short
circuit current protection. The ultimate breaking capacity
of the breaker is the highest symmetrical short circuit
fault current that the breaker is designed to break, and the
breaker manufacture is required to guarantee this level of
performance for one time only. Ics or service breaking
capacity must be guaranteed at least 3 times.
Realistically, the value of Icu is not practical when
considering fault calculations in a distribution system, and
often manufacturers aim for achieving Ics=Icu.
Ultimate or rated short-circuit breaking capacity
(Icn - EN 60898)
A breaking capacity for which the prescribed conditions,
according to a specified test sequence do
not include the capability of the MCB (Miniature Circuit
Breakers) to carry 0.96 times its rated current for the
conventional time.
Ultimate short-circuit breaking capacity
(Icu - EN 60947-2)
A breaking capacity for which the prescribed conditions,
according to a specified test sequence do
not include the capability of the MCB to carry its
rated current for the conventional time.
Service short-circuit breaking capacity
(Ics - EN 60898)
A breaking capacity for which the prescribed
conditions according to a specified test sequence
include the capability of the MCB to carry 0.96
times its rated current for the conventional time.
Service short-circuit breaking capacity
(Ics - EN 60947-2)
A breaking capacity for which the prescribed
conditions according to a specified test sequence
include the capability of the MCB to carry its rated
current for the conventional time.
Icu - ultimate short-circuit breaking capacity
a breaking capacity for which the prescribed conditions according to a specified test sequence do not include the capability of the circuit-breaker to carry its rated current continuously
Ics - service short-circuit breaking capacity
a breaking capacity for which the prescribed conditions according to a specified test sequence include the capability of the circuit-breaker to carry its rated current continuously
Icw - rated short-time withstand current
The rated short-time withstand current of a circuit-breaker is the value of short-time withstand
current assigned
Icm - short-circuit breaking (or making) capacity
a breaking (or making) capacity for which the prescribed conditions include a short circuit
MY QUATION IS ABT THE MAIN POWER TRANSFORMER IN STEEL
PLANT , I WISH TO KNOW THAT WHY TRANSFORMER PROTECTION NOT
TRIP AS CABLES ON THE SECONDAY SIDE IS WATER COOLED.
TRANFORMER DETAIL
NORMAL KVA--150 KVA
PRIMARY VOLTAGE --34.5 KV
SEC.NO-LOAD VOLTAGE---1.290-908-690V ( WITH PRIMARY DELTA
CONNECTED)
CONNECTION--D/d (EXTERNAL CLOSED)
CONSTANT RATEING FROM--1.290-908V
CONSTANT CURRENT FROM--908-690
VECTOR GROUP--D III
What is the List of Equipments, Instruments, Components
required in Transmission of electricity from 1 substation
to other substation(The equipments required in substation
too)?
What are the differnt IS standrds used for above equipments
in Industry?
please design a rectifier with batteries for below requirement
and also explain how you calculate this solution,
Load = 700Amp DC
Backup time = 6 hour.
please explain briefly ?????
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