IS200EGDMH1A GE EX2100 GND Detect Card

Description:

The IS200EGDMH1A model is an exciter field ground detector module, which is what the functional abbreviation of EGDM stands for. During installation, this module will mount in the exciter power backplane rack and will be in proximity to the EPSM module. This module operates on a simplex and redundant system, the simplex system requires one EGDM, while a redundant system requires three EGDM modules. The IS200EGDMH1A is used in conjunction with an EXAM module, together these two modules work to ascertain the potential of field ground leakages on any point of the DC or AC side. 

The EGDM is a double slot, double height (6U) form factor board that mounts in the Exciter Power Backplane rack (EPBP). A simplex system has one EGDM, while a redundant system has three. EGDM detects field leakage resistance from any point in the field circuit of the generator to ground, either on the ac or dc side. The field ground detector applies a low frequency square wave to the sense resistor connected to the field circuit. EXAM, the attenuator module located in the Auxiliary Panel, senses the voltage across the ground resistor and sends the signal to the EGDM through a nine-conductor cable.

In a redundant system, the set of three EGDM boards are configured as a Controller (C), Master 1 (M1) and Master 2 (M2). The configuration for each EGDM is controlled by a set of program pins on the P2 connector. The C controller receives information from the active DSPX on which EGDM master should provide the drive signal to the sense resistor in the Attenuator Module. The active master receives an Oscillator Signal over the fiber optic link that it converts to a ±50 V signal. This is applied to one end of the sense resistor in the Attenuator Module.

The signal conditioner receives an attenuated (10:1) differential signal from the Sense Resistor. This is a simple unity gain differential amplifier with a high common-mode rejection ratio by an A-to-D converter (Voltage Controlled Oscillator VCO). This feeds a fiber-optic transmitter that is cabled to EISB. The signal conditioner circuitry is powered by an isolated power supply to maintain personnel and equipment safety due to the high common-mode voltage at the Sense Resistor.

Datasheet Link:

IS200EGDMH1A GE EX2100 GND Detect Card PDF Datasheet