EGSA-001Shaft Grounding System

THE INFORMATION CONTAINED HEREIN IS CONFIDENTIAL AND PROPRIETARY TO CUTSFORTH INC. AND SHALL NOT BE

REPRODUCED OR DISCLOSED IN WHOLE OR PART FOR ANY DESIGN OR MANUFACTURE

WITHOUT THE WRITTEN AUTHORIZATION OF CUTSFORTH INC.

Cutsforth 7854 12th Avenue South Bloomington, MN 55425 www.cutsforth.com 800.290.6458 fax 800.398.6530Part No. CED-1007 Rev. F

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Cut-Away View

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Components of theShaft Grounding System

**Copper Rope terminates approximately halfway inside the last section of the Guide Assembly

No. Description1 Metering Switch2 Brush Spring*3 Wear Indicator*4 Removable Brush Holder5 Attachment Arm6 Guide Assembly7 Guide Support Arm8 Copper Rope*9 Shaft (existing equipment)

10 Graphite Lube Brush*11 Grounding Wire (attachment location may vary)

12 Voltage Metering Test Points* EGHK-003 Maintenance

Replacement Kit

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Operational Characteristics:

Normal operating shaft voltage is less than 10 volts AC peak-to-peak.Voltages increasing beyond the normal operating voltage, but less than10 VAC peak-to-peak, will generally not cause bearing damage. However, the increase in voltage does begin to indicate problems. For example: poor shaft grounding from dirty shaft contact surface, generator magnetic dissymmetry, generator excitation rectifier failure, turbine blade wear, failed bearing insulation, etc.

Normal operating shaft current is less than 4 amps DC.

Current increasing beyond the normal operating current, but less than4 ADC, will generally not cause bearing damage. However, the increase in current does begin to indicate the problems described above.

Continuous operation above 10 VAC peak-to-peak or 4 ADC can result in

significant shaft bearing damage.

Monitoring Recommendations:

Voltage and current measurements should be performed at intervals required bythe turbine/generator OEM. These results will give indications of trouble and needed maintenance. Meter devices such as an ungrounded oscilloscope, high-speed strip chart style recorder, or analog DC voltmeter (mV-600 VDC) can be used to measure shaft voltage. The shaft voltage is measured by setting the switch to the left ("METER") and placing the leads from the meter device on the two test points. A typical digital multimeter is not recommended for measuring voltage as the results can be unreliable and quick-acting noisy voltage spikes can be missed altogether.

To measure current, additional modifications to the shaft grounding system are needed.

If existing monitoring equipment will be connected to the Cutsforth Shaft Grounding

System, qualified plant personnel are responsible for connecting the systems together. Due to complexities and variations, Cutsforth does not take responsibility for the operation or function of other manufacturers monitoring systems.

Maintenance Recommendations:

The brushes and copper ropes need to be monitored for wear and replaced whenthe brush is worn past the wear indicator on the copper lead, or the copper rope is worn through more than a third of the diameter. The replacement kit part number is EGHK-003 and is available from Cutsforth at (800) 290-6458 or sales@cutsforth.com <mailto:sales@cutsforth.com>

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SwitchOpen

Meter TestPoints forVoltage

MeterSetting

CopperGrounding Ropes

SwitchClosed

Grounding Wire#2 AWG GreenWire Recommended

Dual GroundSetting

Voltmeter

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Shaft Grounding SystemTurbine Generator

Shaft Rotation

Shaft Grounding Location Diagram

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