Hammond CT400A 400:5 Toroidal Current Transformer, 2-10 VA Burden

The CT400A is a 400:5 toroidal current transformer rated 0.6 - 1.2% accuracy over a 2 - 10 VA burden. Besides direct metering of 400 A circuits, it is the model the series application data uses to demonstrate the multi-turn method.

Like every model in the series, it uses a toroidal core, a two hole mounting bracket and 24" insulated secondary leads finished with crimped ring connectors. The primary conductor can be bare (uninsulated) in circuits up to 600 V (4 KV Hi pot), or insulated for higher voltages. UL E227616 volume #1, file number X0DW2 applies to the series.

Overall dimensions for the CT400A are A 4.75 in (121 mm), B 1.35 in (34 mm), C 4.25 in (108 mm), D 4.00 in (102 mm), E 2.20 in (56 mm) and F 3.87 in (98 mm), with mounting slots G 0.22 in (6 mm) by H 0.37 in (9 mm). The listed shipping weight is 1.61 lbs (0.73 kg); the series table gives 1.8 lb. It is RoHS and REACH compliant.

To measure current, pass the wire carrying the current through the CT window so it acts as the primary winding, then connect the secondary to an ammeter with a 5 A movement. Example "A" in the series data: to obtain an accuracy of 1.2% at 10 VA burden with a ratio of 100:5, use a CT400 and loop 4 primary turns through the window.