GE DS2020ASSAG1 | Analog Signal Acquisition | New Original

Description

Product Introduction

The GE DS2020ASSAG1 functions as the Analog Signal Streaming and Acquisition (ASSA) module within the Mark VIe control platform, providing high-speed, streaming data acquisition for monitoring and diagnostics of turbine and generator performance. This module interfaces directly with the Mark VIe controller via ISBus communication, offering 8 high-speed analog inputs and 2 analog outputs, all with 1 kHz per channel sampling, IEEE 1588 timestamping, and onboard data buffering for transient analysis and post-event diagnostics.

The primary differentiator is the high-speed sampling rate and timestamping capability—the ASSA captures analog signals at 1 kHz per channel, timestamped to 1 µs accuracy, enabling detailed analysis of transient events, startup/shutdown dynamics, and high-frequency vibration or pressure phenomena. The onboard 256 MB buffer stores up to 24 hours of continuous streaming data at full speed, which can be retrieved via ISBus for offline analysis. This eliminates the need for external high-speed data recorders and provides integrated data acquisition within the control system.

Key Technical Specifications

Key Selling Points & Differentiators

• High-Speed Sampling: 1 kHz per channel simultaneous sampling on all 8 inputs—captures high-frequency phenomena (vibration, pressure transients, shaft speed fluctuations) not visible with standard 5 Hz control system sampling.
• IEEE 1588 Timestamping: 1 µs timestamp accuracy synchronized to the plant’s PTP time source—enables correlation of analog data with event logs from other systems (DCS, protection relays, sequence-of-events).
• Onboard Buffering: 256 MB buffer stores 24 hours of continuous streaming data—eliminates the need for external high-speed data recorders and provides integrated transient analysis capability.
• Triggered Recording: Configurable triggers (software, external digital input, or threshold-based) start/stop recording automatically—captures pre- and post-trigger data for event analysis.
• Dedicated Data Streaming Link: High-speed serial link for data retrieval ensures ISBus bandwidth isn’t impacted by large data transfers—control and data acquisition operate independently.
• Integrated Anti-Aliasing Filter: Built-in 400 Hz cutoff filter ensures the sampled data is accurate and free from high-frequency noise—complies with Nyquist requirements.
• Full Live Test Certification: Each unit undergoes a 36-hour burn-in with all 8 analog inputs and 2 analog outputs fully simulated at full sampling rate, timestamp sync validation, buffer integrity testing, and ISBus communication verification. We log the MAC ID, analog calibration constants, and timestamp calibration data for traceability.
• Direct Drop-In Replacement: Form-fit-function compatible with DS2020ASSAG and earlier ASSA revisions. Existing wiring and terminal assignments remain unchanged.
• 90-Day Warranty: Includes technical support and cross-ship replacement within 24 hours if the module fails to communicate, reports incorrect analog values, timestamp sync drifts out of specification, buffer fails to record correctly, or analog outputs drift out of calibration.

Frequently Asked Questions (FAQ)

Q1: What’s the difference between the DS2020ASSAG1 and a standard analog input module like the ACHA?

The ASSAG1 is optimized for high-speed data acquisition, not real-time control. The key differences: (1) sampling rate—1 kHz per channel on the ASSA vs. 5 Hz on the ACHA, (2) IEEE 1588 timestamping for precise event correlation, (3) onboard buffering for continuous data storage, (4) dedicated streaming link for data retrieval, and (5) triggered recording modes. The ACHA is designed for control loops (fuel control, excitation control) where response time matters. The ASSA is designed for monitoring, diagnostics, and transient analysis where capture speed matters. You typically use both types in a Mark VIe system—ACHA for control, ASSA for monitoring.

Q2: What types of applications benefit from the ASSA’s high-speed sampling?

Typical applications include: (1) vibration monitoring—capturing high-frequency vibration data for bearing health analysis, (2) startup/shutdown transient analysis—capturing pressure, temperature, and speed during critical startup sequences, (3) transient event recording—capturing data around a trip or protection event for root-cause analysis, (4) performance testing—capturing high-resolution data for turbine performance calculations, and (5) condition monitoring—trending of high-frequency signals (vibration, pressure pulsation, shaft displacement). The ASSA’s 1 kHz sampling captures signals up to 400 Hz (with the anti-aliasing filter), which covers most mechanical vibration frequencies in turbine applications.

Q3: How does the IEEE 1588 timestamping work, and do I need a PTP time source in my plant?

IEEE 1588 Precision Time Protocol (PTP) is a network-based time synchronization protocol. The ASSA receives PTP sync messages from a PTP grandmaster clock in your plant (typically the Mark VIe controller or a separate time server). The module synchronizes its internal clock to the PTP master with 1 µs accuracy. If you don’t have a PTP time source in your plant, the ASSA can still operate—it uses its internal clock for timestamping, but you won’t be able to correlate data with other systems. We recommend using a PTP time source for maximum value. The Mark VIe controller (IS420 series) has PTP capability, or you can use a dedicated time server.

Q4: How do I retrieve the stored data from the onboard buffer?

Data can be retrieved via the dedicated high-speed serial link (not the standard ISBus). The link operates at 10 Mbps, allowing rapid data upload—a full 24-hour buffer (approximately 2 GB of data) can be retrieved in about 30 minutes. The data is retrieved using the ASSA Data Retrieval Tool, which is part of the ToolboxST suite. You can also export the data to CSV or MATLAB format for offline analysis. The ASSA supports continuous streaming to a host PC via this link, so you can view data in real-time during commissioning or troubleshooting.

Q5: Can I trigger the ASSA to start recording when a specific condition occurs (e.g., a turbine trip)?

Yes. The ASSA supports three trigger modes: (1) software trigger—initiate recording via a command from ToolboxST, (2) external digital trigger—a digital input (24 V DC) that starts recording, and (3) threshold trigger—a user-defined threshold on any analog input channel (e.g., vibration above 10 mils). In all modes, the ASSA can record pre-trigger data (configurable up to 1 hour) and post-trigger data (configurable up to 1 hour). This ensures you capture the event leading up to and following the trigger. The trigger configuration is done in ToolboxST’s ASSA configuration block.

Q6: The sampling rate is 1 kHz. Does that mean each channel is sampled at 1 kHz, or is the total throughput 1 kHz shared across all 8 channels?

All 8 channels are sampled simultaneously at 1 kHz each. The ASSA has 8 separate ADC converters, so all channels sample at the same time without any multiplexing delay. The total throughput is 8,000 samples per second (8 channels × 1 kHz). The timestamp for each sample is recorded with 1 µs accuracy. The simultaneous sampling is critical for analyzing phase relationships between channels—for example, comparing vibration on two bearings to determine shaft dynamics.

Q7: What’s the typical lead time for the ASSAG1, and do you recommend stocking spares?

The ASSAG1 is a specialized, lower-volume module—we maintain 2-4 units in inventory. Standard lead time for orders of 1-3 units is 2-4 weeks due to the specialized timestamp validation and buffer testing. For critical turbines requiring high-speed data acquisition, we recommend stocking one spare ASSA per site. If you have a fleet of 10+ turbines, a 10% spare ratio is standard practice. If you need immediate delivery and the ASSA is out of stock, consider using an external high-speed data recorder (e.g., from a third-party manufacturer) connected to the analog signals, though you’ll lose integration with the control system and timestamping. Call our support line for expedited options.

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