SPECIFICATIONS
Part No.: DS3820NGDB1B
Manufacturer: General Electric
Country of Manufacture: United States of America (USA)
Product Type: Field Ground Detector
Availability: In Stock
Series: Mark IV
Functional Description
DS3820NGDB1B is a field ground detector developed by GE. It is a part of the Mark IV control system. This detector is designed to monitor and detect leakage resistance in generator fields, ensuring operational safety and system reliability. It alerts operators through visual indicators and relay-based outputs when resistance drops below acceptable thresholds, helping prevent potential equipment damage or failure.
Features
- Engineered to detect ground faults in generator fields by measuring leakage resistance between any point in the field and ground.
- When the resistance is too low, the module activates an ALARM or FAULT output using its relay contacts. These conditions are visibly indicated on the module's front panel through LED lights, enabling quick identification of the issue.
- Module provides a scaled voltage output corresponding to the leakage current, allowing continuous monitoring of field conditions.
Inputs Required for Operation
The module requires specific inputs to function effectively, including field voltage and power supply connections.
- Field Voltage Inputs: These inputs are sourced from the positive and negative terminals of the generator’s field winding, along with a ground connection. To manage these inputs, external resistors and Metal Oxide Varistors (MOVs) are used. These components protect the module by attenuating voltage levels and suppressing high-voltage spikes. MOVs are rated for a maximum of 480 volts at 1 ampere, and the resistors are selected based on the rated and maximum field voltage.
- Power Input: The module operates on 119/230 V AC, with a frequency range of 50/60 Hz and a maximum power consumption of 30 VA. This makes it compatible with a variety of generator systems.
- Field Flashing Contact: An optional feature allows the relay to be disabled during field flashing. By closing an external contact, operators can prevent false alarms or faults during this process. The contact operates at 5 V DC in open circuit and carries 1 mA in closed condition.
Outputs Provided by the Module
The module delivers outputs through its relay contacts and visual indicators.
- Relay Contacts: The module features two Single Pole Double Throw (SPDT) relays labeled 64A and 64. These relays latch and activate upon detecting a ground fault. The relays are rated for continuous operation at 12 amps, with specific interrupting ratings for non-inductive loads, ensuring robust performance in diverse applications.
- Visual Indicators: Two red LEDs on the front panel provide visual alerts when a fault or alarm condition is detected, allowing operators to take corrective actions swiftly.
Installation
- Location Requirements: The module should be installed in a clean, dry, and vibration-free environment to ensure reliable operation and prevent damage.
- Mounting Instructions: It must be mounted on a vertical surface, providing easy access to the front panel indicators and connections.
- Electrical Connections: Connections must be made in accordance with the module’s elementary diagram. External resistors and MOVs should be positioned near the generator exciter, with a robust ground connection established at this location. If a shaft voltage suppressor is used, it should share the same ground connection to ensure safety and system integrity.
The WOC team is always available to help you with your Mark IV requirements. For more information, please contact WOC.
Frequently Asked Questions
What is DS3820NGDB1B?
It is a Field Ground Detector developed by GE under the Mark IV series.
How does the module detect ground faults?
The module measures field leakage resistance. If the resistance falls below a specified threshold, it activates an alarm or fault through relay contacts and visual indicators (LEDs) mounted on the front panel.
What protection does the module offer against voltage spikes?
The module uses Metal Oxide Varistors (MOVs) and external resistors to suppress high voltage spikes and safely attenuate voltage levels.
Can the module be disabled during field flashing?
Yes, the module's relay can be disabled by closing an external contact during field flashing. This prevents false alarms or faults during the process.
