ABB CTI 21‑P Ex (Material No.: 3BDH000741R1) is a high-precision, multi-channel, isolated temperature input module designed for hazardous and explosive areas.It belongs to the ABB Symphony/Melody series DCS system and is certified to ATEX and IECEx standards, specially engineered for hazardous conditions in Zone 1/2 (gas) and Zone 21/22 (dust).It supports direct connection of RTD, thermocouple, resistance and voltage signals, and performs signal conditioning, linearization, cold junction compensation, lead resistance compensation and 16-bit high-precision AD conversion.Featuring redundant configuration, channel-level diagnostics and fault alarms, it serves as a standard temperature acquisition unit for high-risk applications including petrochemical, chemical, oil & gas and pharmaceutical industries.
Technical Specifications
- Model: CTI 21‑P Ex 3BDH000741R1
- Channel configuration: 32 channels 2-wire / 16 channels 3-wire / 4-wire temperature inputs, individually configurable per channel
- Supported sensors:
- RTD: Pt100, Ni100 (2/3/4-wire), -200…+850℃
- Thermocouple: T/J/E/K/R/S/B/N, -50…+1820℃
- Resistance / Voltage: 0…6000Ω, 0…6V, customizable curves
- Accuracy: ±0.1% FS, temperature drift ±0.05%/10K
- Resolution: 16-bit unsigned AD conversion
- Isolation: Optocoupler galvanic isolation + relay multiplexer channel-level functional isolation
- Explosion protection: Ex d IIC T6 Gb, ATEX/IECEx certified
- Power supply: 20…33VDC, typical 24VDC, power consumption ≤6W
- Operating temperature: 0…50℃ (rack ventilated)
- Protection: Wire break detection 7kΩ±10%, 50/60Hz common-mode rejection >120dB
- Redundancy: Module-level redundancy supported with automatic failover
Installation and Maintenance
Installation Notes
- Rack mounting: Standard subrack slots, align with guide rails / locating pins, secure with locks
- Wiring: Use matching CI 100 / CI 101 wiring units, strictly distinguish 2/3/4-wire systems, single-point grounding of shield
- Explosion-proof compliance: Hazardous area wiring conforms to Ex standards, hot-plugging strictly prohibited
- Grounding: Separate system ground, protective ground and signal ground, grounding resistance ≤4Ω
- Redundancy: Dual modules installed in the same rack with fully redundant power and wiring
Routine Maintenance
- Regular inspection: Clean terminals and vents, check wiring tightness, test wire break / alarm functions
- Calibration: Perform single-point / multi-point calibration according to process cycle, verify with standard resistance / millivolt sources
- Spare parts: Recommend CI 100 wiring units and fuses (T 3.15A slow-blow) as spares
- Troubleshooting: Check power supply, wiring, sensor wire break and channel configuration first, then replace module if needed
Application Areas
- Oil & Gas: Temperature monitoring for drilling platforms, oil & gas processing, and long-distance pipelines
- Refining / Chemical Industry: Temperature measurement in explosion-proof zones of reactors, columns, heat exchangers and storage tanks
- Coal Chemical / Fine Chemical: Explosion-proof reaction kettles, rectification and drying processes
- Pharmaceutical / Bioengineering: Sterile workshops, explosion-proof reactions, and cold-chain temperature control
- Power / Metallurgy: Boilers, gas turbines, and heat exchange systems for hazardous media
- Mining / Warehousing: Temperature safety monitoring in gas and dust explosion-proof areas
Frequently Asked Questions (FAQ)
Q1: What is the core difference between CTI 21 and CTI 21‑P Ex?A: CTI 21 is the standard industrial version for non-hazardous areas only. CTI 21‑P Ex (3BDH000741R1) is the explosion-proof certified version with ATEX/IECEx approval, upgraded channel-level isolation and explosion-proof sealing. It can be used directly in Zone 1/2 (gas) and Zone 21/22 (dust) hazardous areas, with a much higher safety level than the standard version.
Q2: Which sensor types does the module support, and are extra accessories required?A: It supports all common sensor types natively, including Pt100, Ni100 RTDs, full thermocouple series (T/J/E/K etc.), resistance and voltage signals, with no external transmitters needed. Dedicated CI 100/CI 101 wiring units are required and should be purchased together for standard wiring.
Q3: Does a single channel failure affect other channels or the whole system?A: No. The module uses relay multiplexers for independent channel switching. A wire break, short circuit or sensor fault on one channel only triggers an alarm for that channel, without affecting the other 31 channels or causing DCS system shutdown.
Q4: How is module redundancy configured, and what is the switchover response time?A: Two CTI 21‑P Ex modules must be installed in the same subrack with redundant power supplies and independent wiring loops, and redundancy enabled via system software. Failover response time is ≤100ms for bumpless switching and uninterrupted temperature acquisition.
Q5: What is the calibration interval, and is calibration complicated?A: Calibration every 6–12 months is recommended; for harsh conditions (high temperature, strong interference), the interval can be shortened to 3 months. Calibration is straightforward: apply known values using a standard resistance box or millivolt source, then correct offset parameters in ABB DCS configuration software. No advanced expertise is required; on-site engineers can perform it.
Q6: What are the power supply requirements, and what protection mechanisms apply to abnormal power?A: Input voltage: 20–33VDC (typical 24VDC), power consumption ≤6W. Built-in overvoltage and overcurrent protection automatically cuts power and triggers an alarm if voltage is out of range, preventing hardware damage and ensuring data integrity.
Q7: What are the lead time, after-sales support and spare parts availability?A: Standard lead time for in-stock original units is 7–15 working days; custom configurations take 30–45 days. 24/7 remote technical support is provided, with on-site engineer dispatch within 48 hours if needed. A global spare parts supply chain ensures fast delivery of wear parts (wiring units, fuses) for long-term availability.
Q8: What are the core advantages of ABB CTI 21‑P Ex over other brands’ explosion-proof temperature modules?A: Four key strengths:
- Superior compatibility with full ABB DCS series, no extra adaptation cost.
- Higher accuracy with 16-bit AD conversion and multi-compensation algorithms, keeping error within ±0.1% FS.
- Comprehensive safety rating with dual explosion-proof certifications for all hazardous scenarios.
- Reliable after-sales and spare parts support from the original manufacturer, avoiding shortages and support issues common with lesser-known brands.
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