Issue:
How to choose the correct rated over current protection for a 9070 Type T or TF Control Transformer?
Product Line:
LV Transformer
Resolution:
Over current protection (OCP) is dictated by NEC table 450-3(b). In the European community where they choose to not use the NEC but rather use CE, then it is currently dictated by IEC standard EN 60-742. It is the responsibility of the installer to select the appropriate OCP for the device. Square D does have recommended fuse sizes for the primary and secondary to meet the NEC and/or CE. This is found on pages 10 and 11 of the Industrial Control Transformers (Type T and TF) Catalog, document number 9070CT9901 which is available through Literature Fulfillment and on-line at SquareD.com.
Example: With the 9070TF100D1 being a 100VA, 240 x 480 primary to 120V secondary, using both primary and secondary OCPs, and using page 10 of the aforementioned catalog, the proper primary OCP for 240V applied is 1 amp and for 480V applied is 1/2 amp, and the proper secondary OCP is 1-1/4 amp.
Also from that page, it is shown that the primary fuses are midget type (1-1/2`` x 13/32``) class CC time delay type, and the secondary fuse is a midget type and does not need to be a class CC.
How to choose the correct rated over current protection for a 9070 Type T or TF Control Transformer?
Product Line:
LV Transformer
Resolution:
Over current protection (OCP) is dictated by NEC table 450-3(b). In the European community where they choose to not use the NEC but rather use CE, then it is currently dictated by IEC standard EN 60-742. It is the responsibility of the installer to select the appropriate OCP for the device. Square D does have recommended fuse sizes for the primary and secondary to meet the NEC and/or CE. This is found on pages 10 and 11 of the Industrial Control Transformers (Type T and TF) Catalog, document number 9070CT9901 which is available through Literature Fulfillment and on-line at SquareD.com.
Example: With the 9070TF100D1 being a 100VA, 240 x 480 primary to 120V secondary, using both primary and secondary OCPs, and using page 10 of the aforementioned catalog, the proper primary OCP for 240V applied is 1 amp and for 480V applied is 1/2 amp, and the proper secondary OCP is 1-1/4 amp.
Also from that page, it is shown that the primary fuses are midget type (1-1/2`` x 13/32``) class CC time delay type, and the secondary fuse is a midget type and does not need to be a class CC.
Released for: Schneider Electric Canada
Need help?
Product Selector
Quickly and easily find the right products and accessories for your applications.
Get a Quote
Start your sales inquiry online and en expert will connect with you.
Where to buy?
Easily find the nearest Schneider Electric distributor in your location.
Help Center
Find support resources for all your needs, in one place.
