Before installation, remove all original/OEM shaft grounding system equipment and clean the shaft of any surface defects, rust, and other contaminants. Review the documentation for the original/OEM shaft grounding system to plan its removal.
The following figure shows the Shaft Grounding Assembly installed. The installation consists of these main parts:
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Rope guide (A). The portion of the Shaft Grounding Assembly that lays over the shaft and holds the grounding and metering ropes.
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Attachment arm (B). A pipe that connects the Shaft Grounding Assembly to the unit housing. In the figure, the attachment arm is concealed by the High-Frequency Drain resistor (C), which is mounted on the attachment arm.
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High-Frequency Drain (C). An alternate ground path for high-frequency voltage spikes that includes a resistor wired in series.In the figure, it is mounted on the attachment arm.
These are the main tasks in the installation procedure:
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Installing the attachment arm. The length of the attachment arm varies with each installation, so you must temporarily place the Shaft Grounding Assembly on the shaft in order to measure the required length of the attachment arm. The attachment arm is then cut to size, inserted into the mounting hardware, and locked in position with set screws. The attachment arm and Shaft Grounding Assembly are then removed from the unit so that the attachment arm can be welded into the proper angled position. After welding, the entire Shaft Grounding Assembly is secured to the unit.
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Securing the rope guide. The rope guide must be precisely positioned to match the contour of the shaft. This is accomplished by tightening bolts at the top of the rope guide.
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Installing the High-Frequency Drain. THe HFD resistor must be mounted and wired.
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Place the 1/16 in thick rope guide spacer (A) over the shaft (B) (the arrow indicates the shaft rotation direction).
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Set the Shaft Grounding Assembly (C) on the rope guide spacer as shown the following figure. Orient the Shaft Grounding Assembly such that the mid-point of the rope guide is at the 12 o’clock position.
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Temporarily attach the assembly to the shaft using hands, clamps, tape, banding, or a wooden frame.
The location of the connector plate (A) that mounts to the unit may vary, but it must be within 30 inches of the attachment arm connection point (B) on the Shaft Grounding Assembly.
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Using the connector plate as a template, drill and tap four holes (5/16 in-18 x 3/4 in deep) for mounting to the unit.
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Attach the connector plate to the mounting location using the provided 5/16 in-18 x 3/4 in hex bolts and Nordlock washers.
Insert one elbow assembly into the connector plate and one into the adapter located on the Shaft Grounding Assembly. Position the elbow assemblies (A) so they face each other, as shown in the following figure.
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To determine the length of the attachment arm (stainless steel tubing), measure the exact distance between the flanges on each elbow assembly (A), as shown in the following figure.
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Cut the attachment arm to the measured length and install it (B).
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Using a 5/32 in hex key wrench, tighten the three fasteners around the end of each elbow half (A) to 100 in lbs. Use the 5/32 in hex key wrench to tighten the center pivot fastener of each elbow to 70 ft lbs. Do not yet tighten the set screws between the elbows and attachment arm pipe.
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Remove the four hex bolts from the connector plate (B) and the two bolts from the attachment arm adapter connecting to the rope guide. Carefully remove the attachment arm assembly and Shaft Grounding Assembly, while taking care not to disturb the elbow assemblies, as this will cause misalignment.
The attachment arm is made of 300 series stainless steel. TIG welding is the preferred welding method. If a weld filler is needed, AWS E/ER 308, 308L, or 347 are acceptable.
NOTE:
The customer must provide a qualified welder to perform support arm welding.
To weld the attachment arm
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Begin by tack or stitch welding at the marks. The goal is a “stitch” or “fuse” weld. No additional welding material needs to be added at this time. The arm joints simply need to be locked in place by the tacks.
CAUTION
If the tacking step is overlooked and the welder commences to weld the seam, the attachment arm positioning will be compromised, resulting in a distorted arm, which is unusable and must be replaced.
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After tack welding, proceed to weld all of the seams as indicated with the red lines shown in the illustration below. Weld both ends and follow accepted welding practices to minimize distortions that would compromise proper alignments.
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Return the fully welded arm to the Cutsforth technician for final assembly on the generator.
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After assembling the attachment arm, place the Shaft Grounding Assembly back onto the shaft, over the rope guide spacer.
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Connect the attachment arm to the Shaft Grounding Assembly by tightening the two screws (A) shown in the following figure. Torque to 110 in lbs.
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Make any needed fine-tuning adjustments to the orientation to the Shaft Grounding Assembly before locking the rope guide ball and socket joint in place by tightening the three 1/4 in-28 socket head cap screws (B) shown in the following figure. Tighten these bolts by first getting each one snug, then torquing each bolt to 110 in lbs.
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Adjust each rope guide section so that the contact points (A) are touching the 1/16 in rope guide spacer.
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Tighten all the 5/16 in-18 x 5/8 in bolts (B) on the rope guide starting closest to the attachment arm side of the assembly, and then work around from there. Torque all the bolts to 220 in lbs.
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When all rope guide bolts are torqued and the rope guide is secured, remove the rope guide spacer.
This procedure describes how to install the High-Frequency Drain. The purpose of the High-Frequency Drain is to combat the effects of impedance on the ground wire. The High-Frequency Drain does this by dissipating the high-frequency transient voltage spikes through a short ground run with an inline 1 Ω resistor.
To install the High-Frequency Drain
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Find a structure to which the resistor heat sink can be secured. The following example shows the resistor heat sink secured to the attachment arm connector pipe (A).
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Trim a short section of the 12 AWG HFD wire to run from one end of the resistor to the rope guide (B). Connect it to the rope guide assembly using the supplied female disconnect terminal.
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Trim another section of the 12 AWG HFD wire to run from the other end of the resistor to unit case ground (C).