Automationdirect.com Stellar SR44, User Manual

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Chapter 2: Electrical Installation
2.10.1 – Full-Load Current Limit and Short-Circuit Protection (continued)
2.10.2 – External Fuse Requirements
The rating of HRC (High Rupturing Capacity) fuses for motor protection needs to be carefully
analyzed when using a Soft Starter due to the longer start times which are involved. When high
inertia loads (e.g. fans) are being started, special consideration should be given to fuse ratings due
to the extended ramping times. Most fuse manufacturers have an “extended start” or “dual
element” range of fuses intended for this type of application.
The advantage of an HRC fuse becomes evident during a fault current condition. As a result of the
high current, large amounts of heat are created within the fuse, melting the filling of the fuse into
glass. Being an insulator, glass suppresses arc-over and breaks the circuit instantly. This behavior
minimizes the possibility of a continuing, dangerous high arc current.
For semiconductor protection fusing, refer to the table in section 2.10.1.
SR44 Fuse and Current Ratings for Non-UL Applications*
Model
I
e
(A
rms
)
Short Circuit
Current
(RMS)
Fuse
Bussman
FWP 700V
Model #
Edison
E70S
Model #
Amps
SR44-9 9
5kA
FWP-50B E70S50 50
SR44-16 16
SR44-23 23
FWP-80B E70S80 80
SR44-30 30
SR44-44 44
FWP-125A E70S125 125
SR44-59 59
SR44-72 72
10 kA
FWP-200A E70S200 200
SR44-85 85
SR44-105 105
FWP-300A E70S300 300
SR44-146 146
SR44-174 174
FWP-400A E70S400 400
SR44-202 202
SR44-242 242
FWP-500A E70S500 500
SR44-300 300 18 kA
SR44-370 370 FWP-700A E70S700 700
Use these fuses with SR44 soft starters only in NON-UL applications.
SR44 Series Soft Starter User Manual
1st Ed, Rev B 07/31/2019
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