This section describes the installation of the Remote Meter Point and the junction box, and it describes the routing and termination of the signal cables and ground wires.
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Mount the junction box A and the Remote Meter Point or Assurance Monitoring System enclosure B.
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Connect the signal cables to the junction box C and the Remote Meter Point or Assurance Monitoring System D.
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Connect the ground cables to unit case ground E.
This article covers the placement and mounting requirements for the junction box and the Remote Meter Point or Assurance Monitoring System enclosure.
The junction box A requires one strut channel rail B. The junction box receives cable from the rope guide assembly.
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Drill and tap two 5/16 in-18 holes 3/4 in deep in a suitable grounding location on the outside of the unit case to attach the grounding ring terminals (3/8 in diameter terminal). One hole is for the junction box ground (A), and one is for the Remote Meter Point or Assurance Monitoring System ground (B).
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Cut the supplied grounding and signal cable to the appropriate length to run from the Shaft Grounding Assembly to the junction box.
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Cut the supplied 4-twisted-pair signal cable to the appropriate length to run from the junction box to the Remote Meter Point or Assurance Monitoring System.
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Run an 8 AWG conductor and an 18 AWG coaxial cable from the junction box and the Remote Meter Point or Assurance Monitoring System, respectively, to the unit case grounding ring terminals.
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Total ground conductor length from Shaft Grounding Assembly to unit case shall not exceed 47 ft (14.3 m).
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Signal cable length from Shaft Grounding Assembly to monitoring system shall not exceed 30 ft (9.1 m).
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Ground conductor shall not have any sharp bends or service loops anywhere in the run.
The turbine case is the preferred grounding location. The ground conductor should run the shortest route possible, up to a maximum of 47 ft.
NOTE:
Do not run the ground wire an excessive distance in an attempt to terminate to an existing grounding pad. A short run is the best run.
Grounding to the generator case is an alternate option that should be used if it facilitates a shorter overall ground run. However, it typically results in a much noisier ground reference and may introduce unwanted interference, especially when measuring with a handheld oscilloscope.
Junction box
Remote Meter Point or Assurance Monitoring System
For system wiring, refer to EGSK-301 Assurance Monitoring System Wiring Diagram and EGSK-201 Remote Meter Point Wiring Diagram. These diagrams represent the entire grounding system, including the Shaft Grounding Assembly, junction box, and Assurance Monitoring System or Remote Meter Point.
You calibrate the Remote Meter Point using two trimmer potentiometers on the Remote Meter Point:
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Gain trimpot
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Calibration trimpot
The gain trimpot is factory set. Do not adjust it unless specifically instructed to do so by Cutsforth Support.
To adjust the gain trimpot
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Turn the trimpot
in any direction to the farthest extent until there is an audible click.
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Turn the trimpot in the other direction for 15 turns and mark the position with a permanent marker or similar.
The calibration trimpot allows you to calibrate the Hall effect sensor (ground current sensor) so that it reads accurately.
To set the calibration trimpot
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After hardware installation and all wiring is complete, remove the grounding and metering ropes from the Rope Guide Assembly so that no current is flowing through the ground conductor.
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Activate the current sensor (push and hold the button on the Remote Meter Point faceplate) while measuring the voltage at the + CURRENT SENSOR and - CURRENT SENSOR test points.
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Turn the trimpot
On a meter that reads two decimal places, a reading of 0.00 V should be attainable, but on a meter that measures to three places (0.000) it may not be possible to adjust all the way to 0.000 V. +/- 0.009 V or less is acceptable.
Perform this procedure to confirm the proper wiring of the junction box and Remote Meter Point or Assurance Monitoring System.
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Remove ropes from the Shaft Grounding Assembly. See the Removing a Rope section in Replacing a Rope Refresh Kit | Series 2.
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Check that continuity exists between the Remote Meter Point or Assurance Monitoring System panel ground points and turbine ground.
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Check that continuity exists between the Remote Meter Point or Assurance Monitoring System panel shaft voltage test point and the metering rope.
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Install ropes into the Shaft Grounding Assembly. See the Inserting a Rope section in Replacing a Rope Refresh Kit | Series 2.
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Measure the resistance between the shaft and the case to which the ground connection is made and confirm it is less than 1 ohm.