GE DS3820DMCC

Key Parameters

• Channels: 8 digital inputs

• Input Voltage Range: 80–150 V AC/DC (nominal 120 V AC/DC)

• Input Current: 5–15 mA per channel

• Input Impedance: >10 kΩ

• Isolation: 1500 V RMS (channel-to-backplane); 500 V RMS between channels

• On-state Threshold: ≥70 V AC/DC

• Off-state Threshold: ≤30 V AC/DC

• Time-Stamping Resolution: 1 ms (per channel, absolute timestamp)

• Change-of-State (COS) Detection: Yes – captures every state transition with timestamp

• COS Latching: Per-channel latch – holds state change until manually or automatically reset (software-configurable)

• Diagnostics: Open-wire detection, short-circuit detection, per-channel LED status, blown-fuse indication

• Input Filtering: Software-selectable 0.5–50 ms debounce

• Event Buffer: 256 events per channel

• Power: 24 V DC backplane power, ≤3.5 W (plus external 120 V field supply)

• Operating Temperature: –40°C to +70°C

Advantages

• Wide-range AC/DC inputs – accepts 80–150 V AC or DC; eliminates separate modules for 120 V AC and 120 V DC.

• COS latching output – holds state changes until reset; ideal for first-fault indication and persistent alarm annunciation.

• High-resolution time-stamping – 1 ms resolution per channel; essential for sequence-of-events (SOE) recording in high-voltage systems.

• Change-of-State (COS) detection – captures every state transition; reduces PLC CPU load by only reporting changes.

• Open-wire and short-circuit diagnostics – detects wiring faults (broken wires, sensor shorts) for proactive maintenance.

• Per-channel filtering – independently configurable 0.5–50 ms debounce; eliminates false triggers from contact bounce and noise.

• Event buffer – stores up to 256 events per channel; prevents data loss during communication bus congestion.

• Optical isolation – protects backplane from high-voltage transients and ground loops.

• Hot-swappable – replace without rack power-down.

• High channel density – 8 channels in a single slot; saves rack space.

Applications

• Power generation – sequence-of-events recording with persistent fault latching for turbine trips, breaker operations, and protection relay activation (120 V AC/DC)

• Substations – monitoring circuit breaker status, disconnect switches, and protective relay contacts with SOE and first-fault latching

• Motor control centers (MCC) – critical alarm monitoring with time-stamped logs and latching indication for 120 V AC control circuits

• Emergency shutdown (ESD) systems – monitoring safety contacts with latching alarm indication for operator response

• Oil & gas pipelines – valve status monitoring with event history and alarm latching for leak detection

• Switchgear monitoring – breaker trip and alarm contact status with time-stamped event recording and persistent fault latching

• Retrofit projects – replacing legacy 120 V AC relay-based SOE and latching systems with PLC control

Competitor Comparison

The DS3820DMCC is the high-voltage latching SOE variant of the diagnostic input family. Compared to the standard DS3820DIMC, it adds per-channel COS latching – critical for first-fault detection and persistent alarm systems – while maintaining the same wide-range AC/DC input capability. Against standard 120 V input modules without SOE or latching, the DS3820DMCC adds full sequence-of-events recording, diagnostics, and latching annunciation, enabling comprehensive root-cause analysis of trips and faults. For power and substation applications requiring both SOE and latching in 120 V circuits, the DS3820DMCC delivers the most complete solution.

Selection Tips

• Choose DS3820DMCC when you need sequence-of-events recording AND persistent fault latching for 120 V AC/DC circuits – ideal for power generation, substations, and MCCs.

• Ideal for applications requiring root-cause analysis of trips, breaker operations, and protective relay activations with first-fault detection.

• Verify the input voltage matches your field devices – covers 80–150 V AC/DC.

• Consider the latching reset method – software reset (via PLC) or manual reset (external pushbutton) – configurable per channel.

• Consider the event buffer size – 256 events per channel is sufficient for most SOE applications.

• Not suitable for 24 V DC sensors – use the DS3820DMCB family for low-voltage systems.

• Ensure your PLC/DCS can receive and process time-stamped data and latch reset commands.

Precautions

• Time synchronization: Requires accurate time sync from the backplane (e.g., IRIG-B or network time protocol) – without sync, timestamps are relative only.

• Latching behavior: The latch holds the state change until reset. Configure the reset mechanism carefully – automatic reset may clear alarms before operator acknowledgment; manual reset ensures operator visibility.

• Event buffer management: Upload events regularly to avoid buffer overflow – the module does not overwrite old events.

• Filtering: Longer filter settings (50 ms) improve noise immunity but delay event detection – match to your application requirements.

• Input wiring: Do not mix AC and DC field supplies on adjacent channels – while the DS3820DMCC supports both, mixed use may reduce noise immunity.

• Open-wire detection: Requires proper pull-up/pull-down resistors in the field wiring – verify your sensor wiring supports this feature.

• Power: Requires external 120 V field supply – do not exceed 150 V. The DS3820DMCC uses backplane power for logic only.

• Grounding: Maintain proper grounding to avoid ground loop errors that could affect time-stamping accuracy.

• Spare: Keep one spare DS3820DMCC for critical SOE/latching applications – high-voltage modules with combined features typically have longer lead times.