Isolated Analog Signal Converter K Type
Isolated Analog Signal Converter K Type AC-TCK-420
The AC-TCK-420 is an industrial DIN-rail thermocouple transmitter engineered to convert low-millivolt signals from Type K (Chromel-Alumel) thermocouples into an isolated standard analog signal (4–20mA, 0–20mA, or 0–10V DC). Equipped with high-precision internal Cold Junction Compensation (CJC) and sensor burnout alarm detection, it delivers highly accurate and linear temperature measurements across broad industrial temperature spans up to +1370 °C. Engineered with 3-way galvanic isolation (1,500V AC across input, output, and power supply), it protects control equipment against ground potential shifts, high common-mode voltages, and industrial electrical noise common in furnace and thermal processing applications.
Key Features
- 3-way 1.5 kV AC galvanic isolation (input, output, and power)
- Type K thermocouple input (NiCr-NiAl)
- Internal cold junction compensation (CJC)
- Factory customizable temperature spans across -200 °C to +1370 °C
- 4–20mA active current loop output driving loads up to 500 Ω
- Fast response time (≤ 10 ms) for high-temperature process control
- Sensor burnout protection with visual alarm indicator (
ALM) - 24V DC industrial power supply input
- Slim 25 mm DIN rail mountable housing
- Dimensions: 110 mm × 47 mm × 25 mm
Ordering Information
| Product Code | Description |
|---|---|
| AC-TCK-420 | Isolated Thermocouple Converter K-Type to 4–20mA (24V DC, 3-Way Isolated) |
| AC-TCJ-420 | Isolated Thermocouple Converter J-Type to 4–20mA (24V DC, 3-Way Isolated) |
| AC-PT100-420 | Isolated Analog Signal Converter Pt 100 (4–20mA, 24V DC, 3-Way Isolated) |
| AC-PT1000-420 | Isolated Analog Signal Converter Pt 1000 (4–20mA, 24V DC, 3-Way Isolated) |
| AC-RES-420 | Isolated Resistance Signal Converter 0–5k \(\Omega\) to 4–20mA |
| SPD-20MA | 4–20mA Surge Protection Device |
| USS20M24V-D | Current Source Simulator 0/4 to 20mA with Display |
Applications
- Industrial Furnaces, Kilns & Ovens: High-temperature monitoring in heat treatment, annealing, and ceramic firing operations.
- Boiler & Combustion Exhaust Gas Monitoring: Measuring stack and flue gas temperatures with ground loop isolation.
- Metal Casting & Foundry Operations: Monitoring molten metal handling and mold temperatures up to 1200 °C.
- Plastic Extrusion & Injection Molding: Barrel zone and nozzle temperature measurement for PID heat controllers.
- Incineration & Flare Stacks: Robust thermocouple signal transmission over long industrial cable paths.
Specifications
| Parameter | Value |
|---|---|
| Mounting Type | 35 mm DIN Rail Mounting |
| Dimensions | 110 mm x 47 mm x 25 mm (L x H x W) |
| Weight | 100 g |
| Enclosure Material | Industrial Grade ABS |
| Operating Temperature | -20 °C to +55 °C |
| Storage Temperature | -40 °C to +85 °C |
| Relative Humidity | 5% to 95% RH (non-condensing) |
Electrical Specifications
| Parameter | Specification |
|---|---|
| Power Supply Voltage | 24V DC \(\pm 10\%\) |
| Operating Current | 100 mA @ 24V DC |
| Sensor Input Type | Type K Thermocouple (Chromel-Alumel, NiCr-NiAl) |
| Cold Junction Compensation | Integrated internal precision CJC |
| Temperature Range | Customizable from -200 °C to +1370 °C |
| Measurement Accuracy | Class 0.2% of Full Scale @ 25 °C (1–2 °C) |
| Output Signal Range | 4.00 mA to 20.00 mA (or 0–20 mA / 0–10V DC on request) |
| Maximum Output Load Resistance | \(R_L \le 500\,\Omega\) |
| Response Time | \(\le 10\text{ ms}\) (0–90% TYP) |
| Galvanic Isolation Barrier | 1,500 V AC / 1 min (3-Way: Input / Output / Power Supply) |
| Status Indicators | PWR LED (Power ON), ALM LED (Thermocouple Burnout / Open Circuit) |
| Burnout Protection | Upscale / Downscale burnout output drive |
| Reverse Polarity Protection | Integrated diode on 24V DC input |
Mechanical Dimensions
Terminal Details & Wiring
Connection Pinouts
| Terminal Block | Pin | Label | Signal | Description |
|---|---|---|---|---|
| Input Terminals | 1 | SLD | Shield | Thermocouple extension cable shield (Earth ground) |
| (Top Block) | 2 | NC | No Connection | Reserved / Not Connected |
| 3 | TC + | Positive Input | Type K Positive Lead (Chromel / Yellow or Green wire) | |
| 4 | TC - | Negative Input | Type K Negative Lead (Alumel / Red or White wire) | |
| Output Terminals | 5 | OUT + | Signal Out (+) | Active 4–20mA Analog Output (+) |
| (Bottom Block) | 6 | OUT - | Signal Out (-) | Analog Signal Ground / Current Return (-) |
| Power Terminals | 7 | PWR + | 24V DC (+) | +24V DC Operating Power Supply |
| (Bottom Block) | 8 | PWR - | 0V DC (-) | Power Supply Ground Return |
Sensor Wiring Configuration
- Connect the positive thermocouple lead (Chromel) to terminal
3(TC +). - Connect the negative thermocouple lead (Alumel) to terminal
4(TC -). - If using shielded thermocouple extension cable, connect the drain wire/shield to terminal
1(SLD) for electrical noise suppression. - Internal cold junction compensation eliminates the need for an external reference junction.
LED Indications and Diagnostics
| LED | Color | Status | Description |
|---|---|---|---|
| PWR | Green | ON | Normal 24V DC operating power connected |
| ALM | Red | OFF | Normal operation; sensor input within valid range |
| ALM | Red | ON | Sensor open-circuit, broken wire, or burnout detected |
Revision History
| Revision | Date | Description of Change |
|---|---|---|
| Rev 1.0 | 2026-09-09 | Initial datasheet release |
Get the latest version of this datasheet : click here..
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