Product Description
📘 Product Overview
| Field | Details |
|---|---|
| Manufacturer | Foxboro (Invensys) |
| Model Number | 761CNA-AT |
| Description | Single Station MICRO Plus Controller, Housing Mounting, 120 V AC, 32-Position Terminal Block |
| Product Type | Advanced single station cascade controller with EXACT control |
| Applications | Industrial process control, automation, HVAC, batch control |
| Features | EXACT control, dynamic compensation, assignable alarms, algebraic computation, Boolean logic, pulse-driven input, pH display, serial communications, cascade control, passcode security |
| System Compatibility | Retrofit for H-Line, E27 Series, pneumatic 100-Line, and 62HM controllers |
⚡ Electrical Specifications
| Parameter | Specification |
|---|---|
| Power Supply | 120 V AC, 50/60 Hz, +10/-15%, 30 VA maximum |
| Transmitter Power Supply | 25 V DC with 250 Ω resistor for two 4-20 mA transmitters; optional 65 V DC for one 10-50 mA transmitter |
| Input Signals | - Analog: 4-20 mA DC (standard, across 250 Ω resistors); 1-5 V DC (by removing resistors); optional 10-50 mA DC - Thermocouple: Type J, K, E (requires E93 transmitter) - RTD: Platinum IEC 100/SAMA 100, -200 to +850°C - Frequency: 1-9999 Hz (compatible with E83 Vortex, 81/82 Turbine Flowmeters) - Pulse Up/Down: 1-9999 Hz pair, compatible with 62HM controller |
| Maximum Inputs | 4 analog (4-20 mA/1-5 V/10-50 mA), 1 thermocouple, 1 RTD, 2 frequency, 1 pulse up/down pair |
| Output Signals | - Control: 4-20 mA into 500 Ω max (optional isolated or 10-50 mA into 660 Ω) - Auxiliary: 1-5 V DC into 2 kΩ min - Discrete: 2 nonisolated NPN transistor switches, 50 V DC max, 250 mA max, 100 µA leakage |
| Discrete Inputs | 2 nonisolated contact/transistor switches, 5 V DC nominal, 1 mA max |
| Signal Connections | 32-position terminal block, compression terminals for up to 2.5 mm² (14 AWG) wire |
| Power Connections | 3-position terminal strip with 8-32 screw connections |
🔌 Functional Specifications
| Parameter | Specification |
|---|---|
| Control Functions | - Primary Controller: P, I, PD, PI, PID, EXACT; options: nonlinear extender, ratio, tracking, external reset/limits, batch control - Secondary Controller: P, PI (enabled for cascade), ratio, external limits |
| EXACT Control | Microprocessor-based self-tuning, adjusts based on real-time process dynamics; user-selectable damping/overshoot; can be toggled on/off |
| Dynamic Compensation | Lead/lag, impulse, dead time (0-200 min each); dead time precedes lead/lag; individual follow switches; execution 10x/sec (5x/sec for complex configs) |
| Alarms | 4 dual-level alarms with deadband, Boolean output; supports High/High, High/Low, Low/Low, Absolute, Deviation, Rate-of-Change, Latching/Nonlatching/Permissive |
| Calculations | 3 independent blocks (CALC 1-3); operators: +, -, ×, ÷, √, Boolean gates; supports direct inputs, constants, and prior calculation results |
| Boolean Logic | 5 single-input gates (DIRECT, NOT), 5 dual-input gates (OR, NOR, AND, NAND, XOR, NXOR); 18 function switches |
| Signal Conditioning | Square, square root, 2 characterizers (10/15 segments) |
| Signal Distribution | 25 internal signals (conditioned/unconditioned inputs, control outputs, calculations) |
| Control Mode Limits | - Proportional Band: 1-8000% - Integral: 0.01-200 min/repeat - Derivative: 0-100 min - Ratio: 0-5 |
| Input Filter | Second-order Butterworth, 0-10 min adjustment time |
| Serial Communications | RS-485 port; supports configuration download, polling, parameter read/write; compatible with Foxboro F6501A converter (up to 90 controllers) |
| Memory | Nonvolatile (NOVRAM), retains settings during power failure, no batteries |
| Configuration | Front panel keypad, interactive prompting; copy feature via NOVRAM and K0143DV accessory |
| Display | Fluorescent alphanumeric (2x9 characters), 3x50-segment bar graphs, alarm symbol, status indicators; ±0.1% resolution (numeric), ±2% (bar graphs) |
| Security | Passcode protection for configuration changes |
🌡️ Environmental Specifications
| Parameter | Specification |
|---|---|
| Operating Temperature | 5 to 50°C (40 to 120°F) |
| Relative Humidity | 5 to 95% non-condensing |
| Ambient Temperature Effect | ±0.1% (set point), ±0.5% (analog input/output), ±0.2% (frequency), ±0.5°C (RTD) for 30°C change |
| Humidity Effect | ±0.1% of span for 95% RH at 30°C wet bulb |
✅ Performance Specifications
| Parameter | Accuracy |
|---|---|
| Set Point (Local/Remote/Ratio) | ±0.1% of span |
| Input (Analog/Frequency/RTD) | ±0.1% / ±0.1% / ±0.5°C |
| Output (Valve/Retransmitted) | ±0.5% / ±0.25% |
| Linearization (RTD/Thermocouple) | ±0.5°C |
| Control Modes | ±5% (proportional band), ±5% (integral >0.1 min), ±5 s (derivative <0.1 min) |
| Alarms (Absolute/Deviation/Rate) | ±0.1% |
| Calculations | ±0.1% |
| Frequency Response | Flat to 3 Hz (analog input to output) |
| Output Noise | 0.25% peak-to-peak maximum |
| Supply Voltage Effect | ±0.1% of span for +10/-15% AC change |
🔧 Physical Specifications
| Parameter | Specification |
|---|---|
| Mounting | Housing-mounted to panel |
| Signal Connections | 32-position terminal block, compression terminals for up to 2.5 mm² (14 AWG) |
| Power Connections | 3-position terminal strip with 8-32 screw connections |
| Approximate Mass | 4.5 kg (10 lb) |