The CB-4 is designed as a connection point between a TRIO or other portable data collector and permanently installed sensors / transducers for up to four locations.
Permanently mounted transducers are typically used in places where the technician is not able to easily access the machine due to safety or other considerations. This application note covers installation and use of the CB-4 remote sensor connection box.
Each terminal strip represents a triaxial test location that is identified by the bar-code on the front panel. Setting up the test location in the ExpertALERT software is exactly the same as if the test location were accessible. Care must be taken in connecting the wires between the transducers and the CB-4 to ensure orientation of the three axes are correctly defined in the software.
Assembly and Mounting
1. Open the enclosure door and remove the top two screws to allow the panel to swing open. Inside are the following parts:
a. Mounting flanges and mounting hardware b. Watertight fittings and nuts (12)
c. Watertight fitting plugs (11)
2. Install the mounting flanges to the bottom of the enclosure using the ¼-20 flat head screws. The mounting holes should extend away from the enclosure, with the mounting holes exposed. See figure 1.
3. Install the watertight fittings in the pre-drilled holes. Insert the fitting from the outside of the enclosure, and tighten the nut on the inside. Install the fittings in one row first, and tighten the fittings before proceeding to the next row. Fittings that will not have a cable installed will be plugged in a following step.
4. Secure the panel in the closed position with the previously removed screws.
5. Mount the enclosure in an accessible location that will allow protected cable runs to the enclosure. Mounting hole dimensions are shown in Figure 1 above. The enclosure requires clearances of about 6” x 9” with a depth of about 6”. The enclosure waterproof door is hinged on the left and has a locking device on the right side.
1. Proper mounting of the accelerometers is critical to obtaining quality data. Therefore, ensure that the mounting pads have solid metal-to-metal contact and are located in the vibration transmission path on a bearing housing. Additionally, ensure optimum transmission of high-frequency vibration by applying a thin film of silicon lubricant between the accelerometer and the mounting pad.
2. Route the cables from the transducers to the enclosure using care to provide a protected path. Anchor the cable near the transducer with slack between the anchor point and transducer to prevent cable induced forces on the transducer. Number the cables to prevent confusion when making connections later.
3. Run each cable through a watertight fitting installed during the assembly and mounting steps above.
4. Figure 2 shows the terminal strip locations on the back of the CB-4 panel. Note that when the panel is hinged open, the upper connector is farthest forward. Strip cable leads back approximately 3/8” to prepare them for insertion in the terminal block. If necessary, the terminal block is removable to allow easier access to insert the wires into the terminals.
5. Connect the first accelerometer’s ‘hot’ lead to the terminal block labeled “ACC #1 (+)”. Connect its ‘low’ or ‘ground’ lead and cable shield to the (-) terminal. Verify polarity of wires before connecting to avoid permanently damaging the transducer. Repeat this process for each accelerometer at the same test location, or each channel of the triaxial accelerometer (up to three per location). If less than three accelerometers are used per location, leave the unused terminals empty. Follow the same procedure for the remaining test locations (up to four).
6. Tighten the glands on all used watertight fittings. Plug any unused fittings with the included plugs and tighten to provide a good seal. Close the panel, and secure it with the previously removed screws. Install the appropriate bar code labels next to the test location on the front panel.
The permanently installed sensors are set up in the database exactly the same way as for a machine you would walk up to for data collection. A bar code, attached to the CB-4 panel, is assigned to teach position on the machine train (e.g. Motor Drive End). The orientation of a test location is defined as a sequence of three letters corresponding to the axis that each channel measures. For example, the orientation “RAT” designates that channel 1 measures vibration in the Radial direction, channel 2 in the Axial direction, and channel 3 in the tangential direction. If using multiple single-axis accelerometers, use the same frame of reference and channel sequence convention as if using a triaxial accelerometer mounted on a bronze disk mounting pad.
Using the CB-4 with a TRIO Data Collector
1. Disconnect the triaxial accelerometer from the data collector.
2. As required, connect an M-12 to M-12, BNC, or 4-pin AMP adapter cable to the data collector.
3. Connect free end of adapter cable to desired connector on CB-4 box. Locate the machine by ID number, survey, or tree structure and initiate data collection for the appropriate location.
4. When data collection is complete, move adapter cable to the next connector on the CB-4, and initiate data collection for the next location. Continue until complete.
A common application for the remote sensor connection box is a cooling tower fan gearbox. For most cooling towers the motor is accessible for walk-around data collection, while the gearbox is near the rotating fan blades and is inaccessible. The CB-4 is mounted near the machine in a location which is safely accessible during fan operation.
In this example it would be feasible to connect 3 more cooling tower fans to the same CB-4 assuming they were close enough and that there was a safe path for laying the cable. Because ICP accelerometers are low impedance devices, cable runs of up to 500 feet are acceptable.
In the diagram below, the motor has a notched mounting pad installed on the motor so it can be monitored with a standard portable data collector and accelerometer. The gearbox is fitted with three permanently installed single- channel accelerometers. Single-channel accelerometers are used because of their low cost when compared with a triaxial accelerometer. The accelerometers are mounted on the gearbox so they will measure vibration in all three axes of motion.