The Circutor TP10 1250/5 (code M78037) is a single-phase split core current transformer that can be clamped around live conductors and flat busbars up to 80 x 120 mm without interrupting the power supply. It steps a 1250 A primary current down to a standard 5 A secondary output and is available across three accuracy classes, making it a practical choice for retrofitting current measurement into large distribution panels and switchboards.

Technical specifications:

• Model: TP10 1250/5
• Circutor code: M78037
• EAN: 8433059401641
• Transformer type: Split core
• System: Single-phase
• Measurement range: 1250/5 A
• Flat strip (busbar) aperture: 80 x 120 mm
• Inner diameter: 80 mm
• Rated burden by accuracy class: Class 0.5 at 7 VA, Class 1 at 15 VA, Class 3 at 28 VA
• Safety factor (SF): 10
• Insulation voltage between terminals S1-S2: 3 kV
• Maximum operating voltage: 0.72 kV AC
• Nominal frequency: 50/60 Hz
• Thermal short-circuit current (Ith): 60 In
• Dynamic current (Idyn): 2.5 Ith
• Dimensions (width x height x depth): 158 x 51 x 193.8 mm
• Enclosure: Self-extinguishing plastic, class V0
• Mounting: Wall-mounted or DIN rail (via accessory)
• Weight: 0.55 kg
• Thermal class: B (130 C)
• Protection class: IP 20
• Working temperature: -5 to +40 C
• Storage temperature: -40 to +85 C
• Relative humidity: 15 to 85% (non-condensing)
• Maximum installation altitude: 1000 m
• Standards: UNE-EN 61869-1, UNE-EN 61869-2, UL 94

Features and benefits:

• Split core design lets the transformer be fitted around live cables or busbars without cutting power, removing the need for planned outages during installation.
• Wide 80 x 120 mm aperture accommodates the large flat busbars and high-current conductors common in main distribution boards and substations.
• Three selectable accuracy classes (0.5, 1, and 3) allow the unit to be matched to energy billing, general metering, or protection relay applications.
• Self-extinguishing V0 enclosure limits fire propagation risk inside electrical panels and switchgear cabinets.
• Dual-frequency rating (50/60 Hz) makes the transformer suitable for use in both European and international power systems.

Applications:

• Retrofitting current sensing into energised distribution boards and motor control centres without service interruption.
• Energy metering and consumption monitoring on 1250 A single-phase circuits in industrial and commercial buildings.
• Providing a 5 A secondary signal to power analysers, multifunction meters, and protection relays.
• Current measurement on large flat busbar installations in switchboards where dismantling is impractical.

Also known as: Circutor TP10 1250/5, TP10 1250/5 M78037, split core current transformer 1250 A, Circutor M78037, split core CT 1250/5 A.