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Industrial Control Transformers
Fuse Protection
35
08/2005
© 1999–2005 Schneider Electric All Rights Reserved
FUSE PROTECTION
UL Standards and the National Electric Code require primary protection for Control Transformers, and
many applications require secondary protection. Historically, the fuse options supplied by transformer
manufacturers were designed for Line-to-Line primary (480 V) and Line-to-Neutral secondary (120 V).
Schneider Electric’s new line of fuse options lets customers obtain both factory installed and field
installed fuse blocks. Factory installation saves you time and labor. For both options, the transformer
footprint is identical to a Type T or Type EO transformer of equivalent voltage, because the fuse block
is mounted above the transformer or on the transformer terminal blocks. This frees up space normally
used by separate fuse blocks.
Schneider Electric offers the most complete offering of fuse options to meet all applications for
protection of the transformers and load applications. These are broken down into Line-to-Line and
Line-to-Neutral protection options for both primary and secondary. Due to space limitations of the
transformers, not all options are available for every VA size. Also, all fuse blocks supplied by
Schneider Electric are 30 amp fuse blocks, which limits the VA for each voltage.
All primary fuse blocks supplied by Schneider Electric require rejection style fuses. Rejection style
fuses offer 100,000 AIC protection to comply with UL Standards. (Non-rejection style primary fuse
blocks are available by request only and can be quoted through your Schneider Electric field sales
office.)
Primary voltages requiring Line-to-Line protection: 200/208/220/230/240/380/400/
415/440/460/480/550/575/600
Primary voltages requiring line-to-neutral protection: 100/110/115/120/277/347
Europe: 220/230/240
Secondary voltages requiring line-to-line protection: 208/220/230/240
Secondary voltages requiring line-to-neutral protection: 120/277
Europe: 220/230/240
NOTE: The following secondary voltages could be either line-to-line or line-to-neutral: 12/24/48
Primary Secondary
Voltage
VA Range without
Primary Protection
VA Range with
Primary Protection
Voltage
VA Range with
Secondary
Protection
550/575/600 25–5000 VA 25–5000 VA 277 25–5000 VA
440/460/480 25–5000 VA 25–5000 VA 220/230/240 25–5000 VA
380/400/415 25–5000 VA 25–5000 VA 208 25–5000 VA
277 25–5000 VA 25–3000 VA 110/115/120 25–2000 VA
220/230/240 25–5000 VA 25–3000 VA 48 25–1000 VA
208 25–5000 VA 25–2000 VA 24 25–500 VA
110/115/120 25–2000 VA 25–1500 VA 12 25–250 VA
Matrix for Choosing Proper Fuse Configuration
Primary Line-to-Line Primary Line-to-Neutral
Primary Without
Protection
Secondary Line-to-Line
No factory installed option Type TF with R12 S22
Secondary Line-to-Neutral
Type TF Type TF with R11 S12
Secondary Without Protection
Type TF with R02 Type TF with R01 Type T product line