Fuse Protection
UL Standards and the National Electrical 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 line of fuse options allows customers to obtain both factory- and field-installed fuse blocks. Factory installation saves you time and labor. For both options, the transformer footprint is identical to a Type T 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 A 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 | 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 |
| 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 |
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Applications for Line-to-Line Primary protection and Line-to-Line Secondary protection, Example would be 480 to 120/240 (Voltage Code D31) Available as field-installed only for 9070 Type T Must order one 9070FB2A(B)—Primary Must order one 9070S22A(B)—Secondary |
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Application for Line-to-Line Primary protection and Line-to-Neutral Secondary protection Example would be 480 to 120 (Voltage Code D1) Available as factory- and field-installed Factory-installed—9070 Type TF or 9070 Field-installed—9070 Type T: 9070FB3A or 9070FB3B |
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Application for Line-to-Line Primary protection and No Secondary protection Example would be 480 to 24 (Voltage Code D2) Available as factory- and field-installed Factory-installed—9070 Type TF with R02 suffix Field-installed—9070 Type T: 9070FB2A or 9070FB2B |
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Application for No Primary protection and Line-to-Line Secondary Example would be 480 to 120/240 (Voltage Code D31) Primary protection done elsewhere in the circuit Available as factory- and field-installed Factory-installed—9070 Type T Field-installed—9070 Type T: 9070S22A or 9070S22B |
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Application for Line-to-Neutral Primary and Line-to-Line Secondary Example would be 277 to 120/240 Available as factory- and field-installed Factory-installed—9070 Type TF with R12 suffix Field-installed—9070 Type T: 9070R12A or 9070R12B |
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Application for No Primary protection and Line-to-Neutral Secondary Example would be 480 to 120 (Voltage Code D1) Primary protection done elsewhere in the circuit Factory-installed options
Field-installed options
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Application for Line-to-Neutral Primary and Line-to-Neutral Secondary Example would be 277 to 120 (Voltage Code D4) Factory-installed—9070 Type TF with R11 suffix Field-installed—9070 Type T: 9070R11A or 9070R11B |
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Application for Line-to-Neutral Primary and No Secondary Example would be 277 to 24 (Voltage Code D24) Factory-installed—9070 Type TF with R01 suffix Field-installed—9070 Type T: 9070R01A or 9070R01B |
Fuse Protection Options
| Protection | Example | Factory Installed Option(s) | Field Installed Option(s) |
|---|---|---|---|
| Line-to-Line Primary and Secondary | 480 to 120/240 (Voltage Code D31) | Not available | 9070FB2A(B)
- Primary 9070S22A(B) - Secondary |
| Line-to-Line Primary and Line-to-Neutral Secondary | 480 to 120 (Voltage Code D1) | 9070 Type TF | 9070 Type T: 9070FB3A or 9070FB3B |
| Line-to-Line Primary and No Secondary | 480 to 24 (Voltage Code D2) | 9070 Type TF with R02 suffix | 9070 Type T: 9070FB2A or 9070FB2B |
| No Primary and Line-to-Line Secondary | 480 to 120/240 (Voltage Code D31) | 9070 Type T | 9070 Type T: 9070S22A or 9070S22B |
| Line-to-Neutral Primary and Line-to-Line Secondary | 277 to 120/240 (Voltage Code D60) | 9070 Type TF with R12 suffix | 9070 Type T: 9070R12A or 9070R12B |
| No Primary and Line-to-Neutral Secondary | 480 to 120 (Voltage Code D1) | 9070 Type T with S12 suffix Secondary Fuse Block - midget fuses 9070 Type T with SF25 suffix Secondary Fuse Block - glass type fuses 9070 Type T with SF41 suffix Secondary Fuse Clips mounted on terminal block |
9070
Type T: Midget type fuse block: 9070FB1A or 9070FB1B Midget type fuse clips: 9070SF41A or 9070SF41B (Limited to single secondary only) Glass type fuse block: 9070SF25A or 9070SF25B Glass type fuse holder: 9070AP2 Side mounted 2-inch x 9/16-inch: 9070AP1 |
| Line-to-Neutral Primary and Line-to-Neutral Secondary | 277 to 120 (Voltage Code D4) | 9070 Type TF with R11 suffix | 9070 Type T: 9070R11 or 9070R11 |
| Line-to-Neutral Primary and No Secondary | 277 to 24 (Voltage Code D24) | 9070 Type TF with R01 suffix | 9070 Type T: 9070R01A or 970R01B |
Description of Accessory Keys
| Catalog Number | Description | |
|---|---|---|
| Accessory Key I | Accessory Keys II, III, IV |
|
| Two-pole fuse block with rejection clips for primary fusing, field mounted on terminal board via Fingersafe cover, 1-1/2-inch x 13/32-inch midget fuse | ||
| One-pole fuse block with rejection clips for primary fusing, field mounted on terminal board via Fingersafe cover, 1-1/2-inch x 13/32-inch midget fuse | ||
| Three-pole fuse block, two poles with rejection clips for primary fusing and one pole standard clips for secondary fusing, field mounted on terminal board via Fingersafe cover, 1-1/2-inch x 13/32-inch midget fuse | ||
| Two-pole fuse block, one pole with rejection clips for primary fusing and one with standard clips for secondary fusing, field mounted on terminal board via Fingersafe cover, 1-1/2-inch x 13/32-inch midget fuse | ||
| Three-pole fuse block, one pole with rejection clips for primary fusing and two poles standard clips for secondary fusing, field mounted on terminal board via Fingersafe cover, 1-1/2-inch x 13/32-inch midget fuse | ||
| One-pole fuse block with standard clips for secondary fusing, field mounted on terminal board via Fingersafe cover, 1-1/2-inch x 13/32-inch midget fuse | ||
| Two-pole fuse block with standard clips for secondary fusing, field mounted on terminal board via Fingersafe cover, 1-1/2-inch x 13/32-inch midget fuse | ||
| Secondary fuse clips mounted on terminal board, prevents the use of Fingersafe covers, only field installable on single voltage secondary units, 1-1/2-inch x 13/32-inch midget fuse | ||
| One-pole fuse block with standard clips for secondary fusing, field mounted using Fingersafe cover notches, prevents the use of Fingersafe covers, 1-1/4-inch x 1/4-inch glass fuse | ||
| One-pole fuse block with standard clips for secondary fusing, field mounted next to transformer using same mounting hardware, 2-inch x 9/16-inch fuse | ||
| One-pole twist fuse block with standard clips for secondary fusing, field mounted next to transformer using same mounting hardware, 1-1/4-inch x 1/4-inch glass fuse | ||
Fuse Sizing, Description, and Catalog Number (by manufacturer)
| Size | Description | Manufacturer | ||
|---|---|---|---|---|
| Bussman | Littelfuse | Gould-Shawmut | ||
| 1-1/2 x 13/32 in. midget fuse | Time delay, rejection-type, class CC | FNQ-R LP-CC |
KLDR CCMR |
ATDR ATQR ATMR |
| 1-1/2 x 13/32 in. midget fuse | Time delay | FNM; FNQ | FLQ; FLM; FLA | ATQ; TRM; GFN |
| 1-1/4 x 1/4 in. | Time delay | TDC-11; MDL; MDQ; MDA | 3AG: 313/315 3AB: 326/325 |
GDL |
These fuses are not supplied by Schneider Electric.
This table is provided for primary fusing recommendation ONLY. Secondary fusing must be specified by the customer.
All primary fuse options offered by Schneider Electric require rejection-type fuses.
Accessories
Fingersafe™ Covers (not supplied with unit) – Compliant with IP2X per EN-60529
| Class | Type | VA Accessory Key* | Description | |||
|---|---|---|---|---|---|---|
| I | II | III | ||||
| 9070 | FSC-1 FSC-2 FSC-23 |
25–200 VA 250–5000 VA N/A |
25–100 VA 150–5000 VA N/A |
N/A N/A 25–5000 VA |
2 covers per kit |  |
Fuse Puller—For ease in installing fuses and finger protection, used with fuse blocks with 1-1/2 in. x 13/32 in. fuses
| Class | Type | VA Accessory Key | Description | ||
|---|---|---|---|---|---|
| I | II | III | |||
| 9070 | FP-1 | ALL | ALL | ALL | Fuse puller kit complies with IP00 per EN-60529, 3 pullers per kit. |
Primary Fusing to Meet NEC
Recommended Fuse Sizes for the PRIMARY (use class CC time delay fuses) to Meet NEC
| VA | 120 Volts | 240 Volts | 480 Volts | 600 Volts | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Primary Current Amperes | Fuse Rating with Secondary Protection | Fuse Rating without Secondary Protection | Primary Current Amperes | Fuse Rating with Secondary Protection | Fuse Rating without Secondary Protection | Primary Current Amperes | Fuse Rating with Secondary Protection | Fuse Rating without Secondary Protection | Primary Current Amperes | Fuse Rating with Secondary Protection | Fuse Rating without Secondary Protection | |
| 25 | 0.21 | 1/2 | 1/2 | 0.1 | 1/4 | 1/4 | 0.05 | 1/8 | 1/8 | 0.04 | 1/10 | 1/10 |
| 50 | 0.41 | 1 | 1 | 0.21 | 1/2 | 1/2 | 0.1 | 2/10 | 2/10 | 0.08 | 2/10 | 2/10 |
| 75 | 0.63 | 1-1/2 | 1-1/2 | 0.31 | 6/10 | 6/10 | 0.16 | 3/10 | 3/10 | 0.13 | 3/10 | 3/10 |
| 100 | 0.83 | 2 | 2 | 0.42 | 1 | 1 | 0.21 | 1/2 | 1/2 | 0.17 | 4/10 | 4/10 |
| 150 | 1.25 | 3 | 3 | 0.63 | 1-1/2 | 1-1/2 | 0.31 | 6/10 | 6/10 | 0.25 | 6/10 | 6/10 |
| 200 | 1.67 | 4 | 4 | 0.83 | 2 | 2 | 0.42 | 1 | 1 | 0.33 | 8/10 | 8/10 |
| 250 | 2.08 | 5 | 3-2/10 | 1.04 | 2-1/2 | 2-1/2 | 0.52 | 1-1/2 | 1–1/4 | 0.42 | 1 | 1 |
| 300 | 2.5 | 6-1/4 | 4 | 1.25 | 3 | 3 | 0.63 | 2 | 1–1/2 | 0.5 | 1–1/8 | 1–1/8 |
| 350 | 2.92 | 7 | 4-1/2 | 1.46 | 3-1/2 | 3-1/2 | 0.73 | 2-1/2 | 1–8/10 | 0.58 | 1–4/10 | 1–4/10 |
| 500 | 4.17 | 10 | 6-1/4 | 2.08 | 5 | 3-2/10 | 1.04 | 3 | 2–1/2 | 0.83 | 2 | 2 |
| 750 | 6.25 | 15 | 10 | 3.13 | 7-1/2 | 5 | 1.56 | 3-1/2 | 3–1/2 | 1.25 | 3 | 3 |
| 1000 | 8.33 | 20 | 12 | 4.17 | 10 | 6-1/4 | 2.08 | 5 | 3–2/10 | 1.67 | 4 | 4 |
| 1500 | 12.5 | N/A | 15 | 6.25 | 15 | 10 | 3.13 | 7-1/2 | 5 | 2.5 | 6–1/4 | 4 |
| 2000 | 16.66 | N/A | 20 | 8.33 | 20 | 12 | 4.17 | 10 | 6 1/4 | 3.33 | 8 | 5 |
Recommended fuse sizes per NEC Article 450-3.
Transformers with primary only, select protection at 125%, if a standard size rating is not available, go to next higher rating.
Transformers with primary only and current rating is less than 9 A, select protection at no more than 167%.
Transformers with primary only and current rating is less than 2 A, select protection at no more than 300%.
Transformers with primary and secondary, select primary protection at not more than 250% and secondary at 125%.
If a standard size rating is not available, go to next higher standard rating.
Primary Fusing to Meet CE
Recommended Fuse Sizes for the PRIMARY (use time delay fuses) for CE Applications
| CE VA Rating | Primary Voltage | |||||||
|---|---|---|---|---|---|---|---|---|
| 120 V | 208 V | 240 V | 277 V | 380 V | 416 V | 480 V | 600 V | |
| 25 | 1/2 | 3/10 | 2/10 | 2/10 | 1/10 | 1/10 | 1/10 | 1/10 |
| 50 | 1 | 6/10 | 1/2 | 4/10 | 3/10 | 3/10 | 2/10 | 2/10 |
| 75 | 1-1/2 | 8/10 | 6/10 | 6/10 | 4/10 | 4/10 | 3/10 | 3/10 |
| 100 | 2 | 1-1/8 | 1 | 8/10 | 6/10 | 6/10 | 1/2 | 4/10 |
| 150 | 3 | 1-8/10 | 1-1/2 | 1-1/4 | 8/10 | 8/10 | 6/10 | 6/10 |
| 160 | 3-2/10 | 1-8/10 | 1-6/10 | 1-4/10 | 1 | 8/10 | 8/10 | 6/10 |
| 200 | 4 | 2-1/4 | 2 | 1-8/10 | 1-1/4 | 1-1/8 | 1 | 8/10 |
| 250 | 4 | 3 | 2-1/2 | 2 | 1-6/10 | 1-1/2 | 1-1/4 | 1 |
| 300 | 5 | 3-1/2 | 3 | 2-1/2 | 1- 8/10 | 1-8/10 | 1-1/2 | 1-1/8 |
| 500 | 7-1/2 | 4 | 3-2/10 | 4-1/2 | 3-2/10 | 3 | 2-1/2 | 2 |
| 630 | 9 | 6 | 5 | 4-1/2 | 4-1/2 | 4-1/2 | 3-1/2 | 3 |
| 1000 | 15 | 8 | 6-1/4 | 6 | 4 | 4 | 4 | 4 |
| 1500 | 15 | 12 | 10 | 9 | 6-1/4 | 6 | 6-1/4 | 5 |
| 2000 | 20 | 12 | 12 | 12 | 8 | 8 | 7 | 7 |
| 3000 | n/a | 25 | 25 | 20 | 15 | 15 | 12 | 12 |
Secondary Fusing to Meet NEC and CE
Recommended Fuse Sizes for the SECONDARY to Meet NEC and CE
| VA | 24 Volts | 120 Volts | 240 Volts | |||
|---|---|---|---|---|---|---|
| Secondary Current Rating | Fuse Rating | Secondary Current Rating | Fuse Rating | Secondary Current Rating | Fuse Rating | |
| 25 | 1.04 | 8/10 | 0.21 | 3/10 | 0.1 | 15/100 |
| 50 | 2.08 | 3 | 0.42 | 6/10 | 0.21 | 3/10 |
| 75 | 3.13 | 5 | 0.63 | 1 | 0.31 | 1/2 |
| 100 | 4.17 | 6 | 0.83 | 1-1/4 | 0.42 | 6/10 |
| 150 | 6.25 | 10 | 1.25 | 2 | 0.63 | 1 |
| 200 | 8.33 | 12 | 1.67 | 2-1/2 | 0.83 | 1-1/4 |
| 250 | 10.42 | 15 | 2.08 | 3 | 1.04 | 1-3/4 |
| 300 | 12.5 | 20 | 2.5 | 4 | 1.25 | 2 |
| 350 | 14.58 | 20 | 2.92 | 5 | 1.46 | 2-1/2 |
| 500 | 20.83 | 30 | 4.17 | 7 | 2.08 | 3 |
| 750 | n/a | n/a | 6.25 | 10 | 3.13 | 5 |
| 1000 | n/a | n/a | 8.33 | 12 | 4.17 | 7 |
| 1500 | n/a | n/a | 12.5 | 15 | 6.25 | 10 |
| 2000 | n/a | n/a | 16.67 | 20 | 8.33 | 12 |
Recommended fuse sizes according to NEC Article 450-3.
Secondary select protection at 125%, if a standard size rating is not available, go to next higher standard size rating.
Current rating is less than 9 A, select protection at not more than 167%.