Manual 35018V1
505XT Digital Control System for Steam Turbines
Woodward
41
Hardware - Analog Inputs (4-20 mA)
AI Description and Features
The Flex500 controller includes eight (8) 4–20 mA input channels for I/O monitoring and control. Each
channel is differential (self-powered) but can be software configured for Loop Power mode. An Isolated
Loop Power (+24 Vdc) is provided for analog input transducers and includes short-circuit/over-voltage
protection. Note: Do not use the Loop Power output to power any other type devices.
Features
•
Eight (8) 4–20 mA Analog Input Channels, 16 bit resolution
•
Differential inputs with high common-mode voltage capability
•
Isolated Loop Power +24 V is provided with short-circuit protection
•
Fast AI channel #8 for special control functions
•
Woodward GAP block, diagnostics, and configuration support
•
GAP configurable update rates of 5 ms to 160 ms
•
GAP configurable for Loop power operation
Table 2-8. Specifications (AI)
Number of channels
8
AI Input Range
0 to 24 mA
AI Input Isolation
0 V channel to channel.
500 Vrms to EARTH and all other I/O (except USB)
AI Accuracy (@ 25 °C)
≤
0.024 mA (0.1% of FS=24 mA)
AI Accuracy (–40, +70 °C)
≤
0.06 mA (0.25% of FS=24 mA)
AI Resolution
~16 bits of full scale
AI Hardware filter
2 poles @ ~10 ms
**Fast channel (ch 8) has 2 poles @ ~5 ms
AI Input Impedance
200 ohms (Rsense = 162 ohms)
AI Loop power output
24 V ±14% (0-250 mA) short circuit & diode protected
AI Loop power Isolation
500 Vrms to EARTH and all other I/O
AI CMRR over temp
> 70 dB @ 50/60 Hz (typical 86 db)
AI CMVR
> 200 V (dc) to EARTH
AI Overvoltage
±36 V (dc) continuous at room temperature
Figure 2-7. Analog Input – Self-Powered Block Diagram