Installation Strategies

The Cutsforth Shaft Grounding and Contact Assemblies both have a minimum/maximum operating temperature range of -15°C (5°F) to 150°C (300°F).

The Cutsforth Shaft Grounding Assembly is installed on the same portion of exposed shaft as the previous grounding equipment.

The Cutsforth Shaft Contact Assembly is installed on an exposed portion of the shaft at the exciter-end of the generator at a location at which a secondary shaft voltage measurement is desired.

Both the Shaft Grounding Assembly and Shaft Contact Assembly must be installed on the “uphill” side of the shaft rotation. Installing on this side of the shaft ensures that the rope does not bunch up or bind up inside the rope guide. The following illustration shows the correct orientation on the left.

Verify that there is adequate spacing on all dimensions of the SGA and/or SCA assemblies including the support arm and mounting point. Consider both the hot and cold operational conditions, and account for thermal expansion when installing in narrow clearance locations. Factors such as generator type may affect the clearances needed to account for thermal expansion.

Avoid mounting the enclosure in areas that approach or exceed this temperature on a regular basis. If possible, avoid mounting the monitoring system in a location that experiences direct sunlight for extended periods of time throughout the day. If sunshine exposure is unavoidable, inquire with Cutsforth about installation of a sun shield.

The monitoring system should be installed in such a way that does not complicate generator disassembly during outages.

The monitoring system should be accessible to personnel for servicing as needed, and for troubleshooting using the Shaft Grounding Assembly test points. However, system surveillance and performance feedback is not viewable at the monitoring system panel.

The monitoring system should be mounted in a location that does not experience excessive vibrations. Mounting directly to rotating equipment, such as a generator, or other structures with known vibrations, is not recommended. All cabling should be strain-relieved near input connectors. Take care to not directionally bias cable connectors when applying strain relief.

The goal when choosing a grounding location is to electrically bond the shaft to the unit case. The unit case is defined by the lower half of either the turbine case, generator case, or coupler case near the Shaft Grounding Assembly to which the shaft can be grounded. Cutsforth suggests drilling and tapping into the lower half of the unit case to create a grounding location close to the Shaft Grounding Assembly.

The location at which the ground wire will terminate should have all paint removed and should be free of all contaminants in order to create a smooth, conductive surface. Structural steel and station ground are examples of unacceptable grounding locations. It is important to note that it is not necessary for the ground conductor to be grounded to an existing generator grounding pad.

The Shaft Ground Monitoring System enclosure is commonly mounted using strut channel provided by the electrical contractor. Cutsforth recommends the use of a floor-mounted strut channel structure, as it is typically less suspect to excessive vibration. If a wall-mounted structure is necessary, Cutsforth recommends vibration isolation mounting means be employed. The image below is a suitable example location.