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YOKOGAWA ZR402G-TEEA/SCT
Product Overview:
The ZR402G-TEEA/SCT is a 4-channel RTD (Resistance Temperature Detector) input module for Yokogawa’s ZR400 Series PLC. The 402 indicates 4 input channels, Type 2 configuration. The -G denotes the module generation/revision. The TEEA suffix specifies the input type as Thermocouple (T) + RTD (EE) mixed input with 4-wire connection, and SCT indicates a special configuration/customer-specific variant within Yokogawa’s ordering system.
Detailed content
Technical Specifications:
| Parameter | Value |
|---|---|
| Number of Channels | 4 channels |
| Input Type | 4-wire RTD (Pt100, JPt100, Pt1000, JPt1000, Cu50, Cu100) |
| Thermocouple Type (TEEA) | K, J, T, E, R, S, B, N, L, U, W (per channel, software selectable) |
| RTD Connection | 4-wire (Kelvin connection) for highest accuracy |
| Measurement Range (RTD) | -200°C to +850°C (Pt100); -200°C to +600°C (JPt100) |
| Resolution | 0.1°C (for Pt100 at 0°C) |
| Accuracy (RTD) | ±0.15°C (at 0°C, Pt100, 4-wire) |
| Cold Junction Compensation (TC) | Automatic, ±0.5°C accuracy |
| Isolation | 500 VAC between channels and CPU bus (1 minute) |
| Conversion Time | 20 ms per channel (4 channels = 80 ms total scan) |
| Power Consumption | 1.2 W (from CPU bus) |
| Operating Temperature | 0°C to +55°C |
| Dimensions | 25 mm (W) × 90 mm (H) × 85 mm (D) |
| Weight | Approximately 100 g |
Material Composition (Wiring Terminals):
- Terminal block: Phosphor bronze with gold plating for corrosion resistance
- Housing: Flame-retardant polycarbonate (UL94 V-0 rated)
Functional Features:
- 4-wire RTD measurement eliminates lead wire resistance error — critical for high-accuracy temperature measurement
- Mixed input capability: each of the 4 channels can be configured as either RTD or thermocouple via software
- Linearization tables stored in module for Pt100, JPt100, and all standard thermocouple types per ITS-90 standard
- Burnout detection: detects open RTD sensor and flags fault
- LED per channel: indicates normal operation, fault, or communication error
Working Principle:
The module uses a constant current source (typically 1 mA) passed through the RTD element via 4-wire Kelvin connection. The two current-carrying wires supply excitation current, while the two sense wires measure the voltage drop across the RTD with negligible current flow, eliminating lead resistance error. The measured voltage is converted by a 24-bit ADC and processed by the module’s firmware using the Callendar-Van Dusen equation (for Pt100) or ITS-90 polynomial tables to calculate temperature. For thermocouple inputs, the module measures the millivolt signal and applies cold junction compensation using an internal temperature sensor.
Advantages:
- 4-wire connection provides highest accuracy — eliminates lead wire resistance errors entirely
- Mixed RTD/TC input per channel — maximum flexibility for diverse sensor types
- ITS-90 compliant — meets international temperature standard
- Burnout detection prevents undetected sensor failures
Applicable Industries:
- Pharmaceutical — precise temperature control for reactors and lyophilizers
- Chemical Processing — reactor and distillation column temperature monitoring
- Power Generation — turbine bearing and winding temperature measurement
- Food & Beverage — pasteurization and sterilization temperature control
Installation Requirements:
- Use 4-wire shielded cable for RTD connections — shield grounded at CPU side only
- Match RTD type in software configuration to physical sensor (Pt100 vs. JPt100)
- Keep RTD lead wires away from power cables (>100 mm separation)
- Insert into ZR400 CPU backplane slot — verify firmware supports ZR402G module
Usage Precautions:
- Never connect 2-wire RTD to 4-wire terminals — will produce significant measurement error
- Do not apply voltage to RTD input terminals — module supplies excitation current only
- Verify thermocouple type matches software setting — mismatch causes large temperature error
- Calibrate using precision temperature simulator annually for critical applications
