Transcript Yes OR No - Cooper Industries

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© 2015 Eaton. All Rights Reserved..
1
Voltage Rating
© 2015 Eaton. All Rights Reserved..
Voltage Rating
• Voltage rating of the OCPD must be equal to or greater
than the system voltage.
• Voltage rating determines the ability of the OCPD
extinguish the arc during an overcurrent condition.
© 2015 Eaton. All Rights Reserved..
3
Voltage Rating
• NEC 240.60(A) permits 300V cartridge fuses to
be used on circuits not exceeding 300V
between conductors or single-phase line-toneutral loads not exceeding 300V.
• NEC 240.60(B) requires fuseholders to reject
fuses with lower voltage ratings.
• NEC 240.60(C) requires the voltage rating to be
marked on the fuse barrel or label.
• NEC 240.61 allows fuses rated 600V or less to
be used for voltages below their rating.
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4
Voltage Rating
• NEC 240.83(E) requires circuit
breakers to be marked with a
voltage rating that indicates the
circuit breaker’s capability to
interrupt overcurrents between
phases or phase to ground.
• Voltage rating can be “straight”
or “slash” rated.
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5
Voltage Rating
• NEC 240.85 covers the requirements for straight
rated and slash rated circuit breakers.
• A straight rated CB (480V) can be applied on systems
that no more than 480 volts between any two
conductors.
• A two-pole circuit breaker applied on a 3-phase,
corner-grounded delta system must be marked 1Φ3Φ.
© 2015 Eaton. All Rights Reserved..
6
Voltage Rating
• NEC 240.85 (Cont)
• A slash rated circuit breaker, such as 480Y/277V, can
only be applied in a solidly grounded circuit where the
nominal phase to ground voltage does not exceed the
lower number (277V) and the phase to phase voltage
does not exceed the larger number (480V).
© 2015 Eaton. All Rights Reserved..
7
© 2015 Eaton. All Rights Reserved..
8
Voltage Rating
3-Pole, 480/277V CB
Three Phase
C
Corner Grounded
Delta system
B
A
Equipment Bonded to Ground
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9
Slash Rated CB Application
480 volts
line to line
Circuit breaker
480Y/277 slash voltage rating
A
480Y/277 Volt
Three phase
Four wire
Solidly grounded
wye system
B
C
N
G
277 volts
line to ground
© 2015 Eaton. All Rights Reserved..
10
Is Slash Rated 480Y/277V Device Permissible?
A
277V
Solidly Grounded
480Y/277V
480V
Click on Answer
B
Yes
OR
480V
No
C
N
© 2015 Eaton. All Rights Reserved..
11
Is Slash Rated 480Y/277V Device Permissible?
A
277V
Solidly Grounded
480Y/277V
480V
B
Yes
OR
480V
No
C
N
© 2015 Eaton. All Rights Reserved..
12
Is Slash Rated 480Y/277V Device Permissible?
A
277V
Solidly Grounded
480Y/277V
480V
B
Yes
OR
480V
No
C
N
© 2015 Eaton. All Rights Reserved..
13
Is Slash Rated 480Y/277V Device Permissible?
A
277V
Solidly Grounded
480Y/277V
480V
B
Yes
OR
480V
No
C
N
© 2015 Eaton. All Rights Reserved..
14
Is Slash Rated 480Y/277V Device Permissible?
Corner Grounded
Delta
A
Click on Answer
Yes
B
480V
OR
No
C
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15
Is Slash Rated 480Y/277V Device Permissible?
Corner Grounded
Delta
Yes
A
B
480V
OR
No
C
© 2015 Eaton. All Rights Reserved..
16
Is Slash Rated 480Y/277V Device Permissible?
Corner Grounded
Delta
Yes
A
B
480V
OR
No
C
© 2015 Eaton. All Rights Reserved..
17
Is Slash Rated 480Y/277V Device Permissible?
Corner Grounded
Delta
Yes
A
B
480V
OR
No
C
© 2015 Eaton. All Rights Reserved..
18
Slash Rated Exercise
System
Secondary
L-L
L-G
Can 480Y/277
Voltage
System Type
Volt
Volt
CB Be Used?
480Y/277
Solidly
Grounded WYE
480
277
Yes
No
480
277
Yes
No
480
480
Yes
No
480
*
Yes
No
480
480
Resistance
Grounded WYE
Delta Corner
Grounded
B Phase
480
Delta
Ungrounded
* Ungrounded delta systems - phase conductors
are capacitively coupled to ground
© 2015 Eaton. All Rights Reserved..
19
Slash Rated Exercise
System
Secondary
L-L
L-G
Can 480Y/277
Voltage
System Type
Volt
Volt
CB Be Used?
480Y/277
Solidly
Grounded WYE
480
277
Yes
No
480
277
Yes
No
480
480
Yes
No
480
*
Yes
No
480
480
Resistance
Grounded WYE
Delta Corner
Grounded
B Phase
480
Delta
Ungrounded
* Ungrounded delta systems - phase conductors
are capacitively coupled to ground
© 2015 Eaton. All Rights Reserved..
20
Slash Rated Exercise
System
Secondary
L-L
L-G
Can 480Y/277
Voltage
System Type
Volt
Volt
CB Be Used?
480Y/277
Solidly
Grounded WYE
480
277
Yes
No
480
277
Yes
No
480
480
Yes
No
480
*
Yes
No
480
480
Resistance
Grounded WYE
Delta Corner
Grounded
B Phase
480
Delta
Ungrounded
* Ungrounded delta systems - phase conductors
are capacitively coupled to ground
© 2015 Eaton. All Rights Reserved..
21
Slash Rated Exercise
System
Secondary
L-L
L-G
Can 480Y/277
Voltage
System Type
Volt
Volt
CB Be Used?
480Y/277
Solidly
Grounded WYE
480
277
Yes
No
480
277
Yes
No
480
480
Yes
No
480
*
Yes
No
480
480
Resistance
Grounded WYE
Delta Corner
Grounded
B Phase
480
Delta
Ungrounded
* Ungrounded delta systems - phase conductors
are capacitively coupled to ground
© 2015 Eaton. All Rights Reserved..
22
Slash Rated Exercise
System
Secondary
L-L
L-G
Can 480Y/277
Voltage
System Type
Volt
Volt
CB Be Used?
480Y/277
Solidly
Grounded WYE
480
277
Yes
No
480
277
Yes
No
480
480
Yes
No
480
*
Yes
No
480
480
Resistance
Grounded WYE
Delta Corner
Grounded
B Phase
480
Delta
Ungrounded
* Ungrounded delta systems - phase conductors
are capacitively coupled to ground
© 2015 Eaton. All Rights Reserved..
23
© 2015 Eaton. All Rights Reserved..
24