TUBE AS 3465590 - Caterpillar

SR4 and SR4B GeneratorsSUPPLEMENT: 06/01/96Engine News; August 1995; Page 23; "Field Installation Procedure For Stator Thermocouples and RTDs".Disregard the August, 1995 article. See the article with the same title in this issue.
--------------- END SUPPLEMENT ---------------Description of Change: Resistive thermo devices (RTDs) and type J thermocouples are typically installed in Caterpillar generators in the stator windings on the drive end. In factory installation, these devices are embedded among the strands of copper magnet wire. Thermocouples are commonly used on random wound generators and RTDs are used on form wound generators. When the thermocouples or RTDs need to be replaced, this procedure provides a method of field replacement. Adaptable To: For field installation, the thermocouples or RTDs should be mounted on the surface of the varnished windings. The following procedure should be used when adding these monitoring devices to an existing generator. This procedure is applicable to all SR4 and SR4B generators equipped with thermocouples or RTDs. 1. Remove the generator shell to allow access to the windings at the drive end of the generator.2. Install six thermocouples/RTDs per generator among the stator coils on the flywheel (exhaust air) end of the unit. Install the devices in the 12 o'clock area, 2 per phase. To differentiate phases, install a pair at the 12 o'clock position. Then, from this first pair, count 6 coils toward the 11 o'clock position and 6 coils toward the 1 o'clock position. Mount a pair of thermocouples/RTDs in each location.3. Clean the surface area of the coil where the devices are to be mounted. Apply epoxy adhesive to the thermocouple/RTD and press it on to the coil surface. Cover the device with a piece of polyester felt pad or similar insulating material. Secure this pad with a nylon cable tie. 4. Run the thermocouple/RTD leads back down the top center of the generator to the end mounted terminal box.5. Reinstall the generator shell.For ordering purposes, thermocouples/RTDs can be referenced in the TIR section of the price list.