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Motor control center intelligent

Fusible Disconnect

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ĨƵƐŝďůĞ ĚŝƐĐŽŶŶĞĐƚ ƐǁŝƚĐŚ ŝƐ ŽŶĞ
type of device used to provide
ŽǀĞƌĐƵƌƌĞŶƚ ƉƌŽƚĞĐƟŽŶ͘
dŚĞ ĚŝƌĞĐƟŽŶ Ă ƚŚƌĞĞͲƉŚĂƐĞ ŵŽƚŽƌ ƌŽƚŽƌ ƚƵƌŶƐ ĚĞƉĞŶĚƐ ŽŶ ƚŚĞ
phase sequence of the incoming power supply. In the following
ĞdžĂŵƉůĞ͕ >ϭ ; Ϳ ŝƐ ĐŽŶŶĞĐƚĞĚ ƚŽ ŵŽƚŽƌ ůĞĂĚdϭ͕ >Ϯ ; Ϳ ŝƐ ĐŽŶŶĞĐƚĞĚ
ƚŽ ŵŽƚŽƌ ůĞĂĚdϮ͕ ĂŶĚ >ϯ ; Ϳ ŝƐ ĐŽŶŶĞĐƚĞĚ ƚŽ ŵŽƚŽƌ ůĞĂĚdϯ͘ tŚĞŶ
power is applied through the “F” contacts, the motor turns in a
ĐůŽĐŬǁŝƐĞ ;ĨŽƌǁĂƌĚͿ ĚŝƌĞĐƟŽŶ͘ Fuse:

ĨƵƐĞ ŝƐ Ă ŽŶĞͲƐŚŽƚ ĚĞǀŝĐĞ͘ dŚĞ
heat produced by overcurrent
Circuit Breakers: causes the current carrying ele-
ŵĞŶƚ ƚŽ ŵĞůƚ ŽƉĞŶ͕ ĚŝƐĐŽŶŶĞĐƟŶŐ
the load from the source voltage.
ŶŽƚŚĞƌ ĚĞǀŝĐĞ ƵƐĞĚ ĨŽƌ ŽǀĞƌĐƵƌƌĞŶƚ
ƉƌŽƚĞĐƟŽŶ ŝƐ Ă ĐŝƌĐƵŝƚ ďƌĞĂŬĞƌ͘
/Ŷ ĂĚĚŝƟŽŶ ƚŽ ƉƌŽǀŝĚŝŶŐ ŽǀĞƌĐƵƌƌĞŶƚ
ƉƌŽƚĞĐƟŽŶ͕ Ă ĐŝƌĐƵŝƚ ďƌĞĂŬĞƌ
WƌŽǀŝĚĞƐ Ă ŵĂŶƵĂů ŵĞĂŶƐ ŽĨ ĞŶĞƌŐŝnj-
ing and de-energizing a circuit.
One key advantage of a circuit
breaker is that it allows a circuit to
ďĞ ƌĞĂĐƟǀĂƚĞĚ ƋƵŝĐŬůLJ ĂŌĞƌ Ă ƐŚŽƌƚ
circuit or overload is cleared by sim-
ƉůLJ ƌĞƐĞƫŶŐ ƚŚĞ ďƌĞĂŬĞƌ͘

Horizontal and VerƟcal Bus:

ďƵƐ ŝƐ Ă ĐŽŶĚƵĐƚŽƌ ƚŚĂƚ ƐĞƌǀĞƐ ĂƐ Ă ĐŽŵŵŽŶ ĐŽŶŶĞĐ-
ƟŽŶ ĨŽƌ ƚǁŽ Žƌ ŵŽƌĞ ĐŝƌĐƵŝƚƐ͘ /ƚ ŝƐ ƌĞƉƌĞƐĞŶƚĞĚ ƐĐŚĞŵĂƚ-
ŝĐĂůůLJ ďLJ Ă ƐƚƌĂŝŐŚƚ ůŝŶĞ ǁŝƚŚ Ă ŶƵŵďĞƌ ŽĨ ĐŽŶŶĞĐƟŽŶƐ
made to it.
dŚĞ ŚŽƌŝnjŽŶƚĂů ďƵƐ ŽŶ ƟĂƐƚĂƌ ŵŽƚŽƌ ĐŽŶƚƌŽů ĐĞŶƚĞƌƐ
ĂƌĞ ŵĂĚĞ ŽĨ ƟŶͲƉůĂƚĞĚ ĐŽƉƉĞƌ ;ƐƚĂŶĚĂƌĚͿ Žƌ ŽƉƟŽŶĂů
ƐŝůǀĞƌͲƉůĂƚĞĚ ĐŽƉƉĞƌ Žƌ ƟŶͲƉůĂƚĞĚ ĂůƵŵŝŶƵŵ͘ dŚĞLJ ĂƌĞ
ĂǀĂŝůĂďůĞ ǁŝƚŚ ϲϬϬ͕ ϴϬϬ͕ ϭϮϬϬ͕ ϭϲϬϬ͕ ϮϬϬϬ ĂŶĚ ϮϱϬϬ
ĂŵƉĞƌĞ ĐƵƌƌĞŶƚ ƌĂƟŶŐƐ͘
In power circuits, such as motor control centers, a bus
is made of heavy-duty metal bars. These bus bars pro-
ǀŝĚĞ ƉŽǁĞƌ ƚŽ ĞĂĐŚ ŽĨ ƚŚĞ ĐŽŵďŝŶĂƟŽŶ ŵŽƚŽƌ ĐŽŶƚƌŽů
ƵŶŝƚƐ͘ dŚĞ ǀĞƌƟĐĂů ďƵƐ ŝƐ ĐŽŶŶĞĐƚĞĚ ƚŽ Ă ĐŽƌƌĞƐƉŽŶĚŝŶŐ
horizontal bus and is isolated from the other bus bars.
dŚĞ ǀĞƌƟĐĂů ďƵƐ ŽŶ ƚŚĞ ƟĂƐƚĂƌ ŵŽƚŽƌ ĐŽŶƚƌŽů ĐĞŶƚĞƌƐ
ĂƌĞ ĂǀĂŝůĂďůĞ ǁŝƚŚ ϯϬϬ ĂŶĚ ϲϬϬ ĂŵƉĞƌĞ ĐƵƌƌĞŶƚ ƌĂƟŶŐƐ͘
'ƌŽƵŶĚ ƵƐ ŚŽƌŝnjŽŶƚĂů ŐƌŽƵŶĚ ďƵƐ ŝƐ ƚLJƉŝĐĂůůLJ tŚĞŶ Ă ĐŽŵďŝŶĂƟŽŶ ŵŽƚŽƌ ĐŽŶƚƌŽů ƵŶŝƚ ŝƐ ŝŶƐĞƌƚĞĚ
ŵŽƵŶƚĞĚ ŝŶ ƚŚĞ ďŽƩŽŵ ϲ͟ ŽĨ ƚŚĞ ƐƚƌƵĐƚƵƌĞ͘ dŚĞ ŚŽƌ- ŝŶƚŽ ƚŚĞ D ͕ ƚŚĞ ǀĞƌƟĐĂů ŐƌŽƵŶĚ ďƵƐ ŝƐ ƚŚĞ ĮƌƐƚ ŝƚĞŵ
ŝnjŽŶƚĂů ŐƌŽƵŶĚ ďƵƐ ŝƐ ƐƚĂŶĚĂƌĚ͘ Ŷ ŽƉƟŽŶĂů ǀĞƌƟĐĂů ĞŶŐĂŐĞĚ͘ >ŝŬĞǁŝƐĞ͕ ǁŚĞŶ ƚŚĞ ƵŶŝƚ ŝƐ ƌĞŵŽǀĞĚ͕ ƚŚĞ ǀĞƌƟ-
ground bus can be connected to the horizontal bus. cal ground bus is the last thing to be disengaged.

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