Overview
The STQ-24 is a compact, split-core current transformer designed for measuring current in electrical installations ranging from 100 to 300 Amperes. This guide provides installation instructions and technical specifications.
For the complete manual, please visit the CIRCUTOR website: www.circutor.com
Important Safety Warnings ⚠️
Before undertaking any installation, repair, or handling operations on the unit's connections, the device MUST be disconnected from all power supply and measurement sources.
Contact the after-sales service if you suspect an operational fault. The device is designed for easy replacement in case of malfunction.
The manufacturer is not responsible for any damage resulting from failure to heed warnings and recommendations, or from the use of non-original products or accessories.
When the device is connected, terminals may be hazardous to the touch. Opening covers or removing elements may expose dangerous parts. Do not use the device until fully installed.
Do not expose the STQ-24 to aggressive or explosive environments.
For measurements on non-insulated conductors, use appropriate personal protective equipment (PPE).
1. Description
The STQ-24 is a split-core current transformer with reduced dimensions. It allows for current measurement in electrical installations from 100 to 300 A.
2. Installation
As a split-core transformer, the STQ-24 does not require cutting any cable or busbar, thus eliminating the need to interrupt the installation's power supply for installation.
3. Connection
The STQ-24 is a pass-through bar type current transformer. The conductor carrying the current to be measured must pass through the internal window of the transformer.
The primary conductor from the connection should be inserted into the transformer on the P1 side and exit on the P2 side towards the load of the installation being measured.
Once the primary is connected, wire the transformer's secondary (S1 and S2) to the measuring device.
Technical Specifications
| Feature | Specification |
|---|---|
| Type | Pass-through bar / Single-phase |
| Primary Current | 100 ... 300 A |
| Secondary Current (In) | .../5A, .../1A, .../0.250A |
| Thermal Short-Circuit Current (Ith) | 60 In |
| Dynamic Current (Idyn) | 2.5 Ith |
| Frequency | 50 Hz - 60 Hz |
| Maximum Operating Voltage | 0.72 kV ~ |
| Insulation Voltage | 3 kV |
| Class | 1, 3 |
| Accuracy Limit | 1.2 In |
| Continuous Overload | 1.2 In |
| Precision Power | 0.1 ... 1 VA |
| Operating Temperature | -5 °C ... 40 °C |
| Storage Temperature | -20 °C ... 75 °C |
| Relative Humidity (non-condensing) | 15 ... 85 % |
| Maximum Altitude | 1000 m |
| Thermal Class | B (130°C) |
| Protection Degree | IP 20 |
| Safety Factor | FS 5 |
| S1, S2 Wire Size | 0.22 mm² (for .../0.250A), 0.52 mm² (for .../1A), 2 mm² (for .../5A) |
| Length (S1, S2) | 1 m |
| Window Size | 24.40 x 23.00 mm |
| Max. Conductor Diameter | Ø 24 mm |
| Dimensions (L x W x H) | 54.8 x 70.5 x 51.6 mm |
| Weight | 0.2 kg |
| Enclosure Material | PC Lexan™ 940-701 |
| Standards | UNE-EN 61869-1, UNE-EN 61869-2 |
Connection Diagram Description
The diagram illustrates the connections for the STQ-24 current transformer. Primary conductors (L1, L2, L3) are connected to terminals P1 and P2. The secondary winding terminals are S1 and S2, which connect to a measuring device. The load is connected after the P2 terminal.
Diagram Visualisation:
A schematic shows the transformer with input terminals labeled P1 and P2, and output terminals labeled S1 and S2. Primary power lines (L1, L2, L3) are shown connecting to P1 and P2. A load is depicted after P2. The secondary wires (S1, S2) are shown leading to a generic "Measuring device".
Rated Current Table
This table details the VA rating for different primary to secondary current ratios:
| Primary Current (A) | Secondary Current (A) | VA Rating (Class 1) | VA Rating (Class 3) |
|---|---|---|---|
| 100 | 0.250 | 0.1 VA | - |
| 100 | 1 | 1 VA | - |
| 100 | 5 | 1 VA | - |
| 150 | 0.250 | 0.1 VA | - |
| 150 | 1 | 1 VA | - |
| 150 | 5 | 1 VA | - |
| 200 | 0.250 | 0.1 VA | - |
| 200 | 1 | 1 VA | - |
| 200 | 5 | 1 VA | - |
| 250 | 0.250 | 0.1 VA | - |
| 250 | 1 | 1 VA | - |
| 250 | 5 | 1 VA | - |
| 300 | 0.250 | 0.1 VA | - |
| 300 | 1 | 1 VA | - |
| 300 | 5 | 1 VA | - |
Note: The table indicates that for Class 3, only certain secondary current ratings (1A and 5A) are specified with 1 VA. The 0.250A secondary rating is only specified for Class 1.
Dimensions
The transformer has the following dimensions:
- Overall Dimensions: 54.8 mm (Width) x 70.5 mm (Height) x 51.6 mm (Depth)
- Window Size: 24.40 x 23.00 mm
- Maximum Conductor Diameter: Ø 24 mm
Visualisation of Dimensions:
A diagram shows the physical outline of the transformer with key measurements indicated. The main body is roughly rectangular with rounded edges. The width is shown as 54.8 mm, height as 70.5 mm, and depth as 51.6 mm. The internal opening (window) is shown with dimensions 24.40 mm and 23.00 mm. The maximum diameter of a conductor that can pass through is indicated as Ø 24 mm.
Technical Service and Contact Information
For technical support or service, please contact CIRCUTOR:
CIRCUTOR SAT:
- Phone (Spain): 902 449 459
- Phone (International): (+34) 937 452 919
- Address: Vial Sant Jordi, s/n, 08232 - Viladecavalls (Barcelona), Spain
- General Tel: (+34) 937 452 900
- Fax: (+34) 937 452 914
- Email: sat@circutor.com
Document Reference: M381A01-44-25B
