Determine the best component locations for your installation by applying the following strategies.
Please review the list of best practices for installation below to help ensure maximum effectiveness of your Cutsforth Shaft Grounding System:
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All Series 1 and Series 2 Shaft Grounding Assemblies (SGAs) shall be installed with a High Frequency Drain (HFD).
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Avoid sharp turns and bends in the grounding wire whenever possible. Bending the conductor can create induction back on the bent wire. While the HFD will aid in dissipating this inductance, it is best to make turns as gradual as possible.
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The grounding conductor shall be routed according to the shortest possible path. When the HFD is installed, it is allowable for the ground conductor to extend up to 47 ft (14 m) in total length when measured from the SGA grounding rope all the way to the finished grounding terminal on the unit case.
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The Assurance Monitoring System shall be mounted such that the segment of conductor between the SGA and the Assurance Monitoring System is no greater than 30 ft (9 m). If the signal lines between the SGA and the Assurance Monitoring System are longer than 30 ft (9m), the monitoring function begins to be diminished.
The Cutsforth Shaft Grounding Assembly is installed on the same portion of exposed shaft as the previous grounding equipment. The Shaft Grounding 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.
The goal when choosing a grounding location is to electrically bond the shaft to the unit case. 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 Assurance Monitoring System has a temperature rating of 70°C (158°F). Avoid mounting the enclosure in areas that exceed this temperature. If possible, avoid mounting the monitoring system in a location that experiences direct sunlight for extended periods of time throughout the day.
The ground conductor must be routed through the Junction Box prior to terminating to the unit case. Therefore, it is a good idea to mount the Junction Box somewhere between the Shaft Grounding Assembly (SGA) and the unit case termination location. This helps eliminate extensive lengths in the ground conductor run. Routing to ground, the Junction Box should be installed between the SGA and the ground location to accommodate a short ground run.
The Assurance Monitoring System contains an interactive control panel and should be placed in a location that is safe and accessible for plant personnel. The monitoring system should be placed at an ergonomic height such that the center of the touchscreen is roughly at eye-level.
The Assurance Monitoring System is commonly mounted using a strut channel rail, as shown in the following figure. If preferred, the enclosure can also be bolted directly to other solid structures.
The generator manufacturer is the best source of information regarding the values that you can expect to see on your generator. We suggest focusing on the data trends more than the specific voltage and current values. For example: Do the values change over time? Are the changes significant? How are the values changing?