Hammond CT50A 50:5 Toroidal Current Transformer, 3.2% Accuracy

The CT50A is the lowest-ratio model in the indoor toroidal CT series, stepping 50 A of primary current down to a 5 A secondary. It suits panel builders and electricians metering small feeders and branch loads with a standard 5 A AC ammeter. Rated accuracy is 3.2% at a 2 VA burden.

Construction is a toroidal design with 24" insulated secondary leads terminated in crimped ring connectors, and every model in the series has a two hole mounting bracket. It is suitable for use with a bare (uninsulated) primary conductor in circuits up to 600 V (4 KV Hi pot), or at higher voltages when a suitably insulated conductor is used. The series is listed under UL E227616 volume #1, file number X0DW2.

Overall dimensions for the CT50A are A 3.75 in (95 mm), B 1.35 in (34 mm), C 3.25 in (83 mm), D 3.00 in (76 mm), E 0.87 in (22 mm) and F 2.87 in (73 mm), with mounting slots G 0.22 in (6 mm) by H 0.37 in (9 mm). The listed shipping weight is 1.3 lbs (0.59 kg); the series table gives 1.3 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. The CT50A also appears in the series application data: to obtain a 25:5 ratio, a CT50 with 2 primary turns looped through the window yields 3.2% accuracy.