RTD6M PD SENSOR BOARD INSTALLATION MANUAL IB07005E Rev.B September 0 PREDICTIVE DIAGNOSTICS 5 Feltl Road, Ste 90, Minnetonka, MN 55, USA Phone (95) 9, Fax (95) 955; Website: www.eaton.com\pd Email: chpd@eaton.com
Eaton Predictive Diagnostics RTD6M PD sensor board manual IB07005E General Notes RTD6M PD Sensor Board is designated for measuring Partial Discharges (PD) in a stator winding of a rotating machine utilizing RTDs embedded into stator winding as PD sensors. RTD acts as RFantenna embedded into a winding that picks high frequency component of an electromagnetic pulse caused by PD. Calibration tests showed that RTDs could be used in assessing PD levels within few slots from its location. A PD signal induced in a stator RTD and wires propagates in the common mode between all three RTD wires and ground (machine frame, stator core) to the closest RTD terminal board located on a machine frame. At that location PD signal could be measured by specially designed sensors. RTD6M PD Sensor Board replaces existing RTD terminal board with no effect on primary RTD function of stator temperature monitoring. It incorporates filter to block high frequency noise signals from the temperature metering system. It can be used with any Partial Discharge measuring equipment with frequency band of 0 MHz. Six coaxial cables could be directly wired to a continuos Partial Discharge monitoring unit or terminated to BNC connectors in a termination box for a portable PD analyzer connection. The board and example of a termination box are shown in Figures and. Figure. RTD6M PD sensor board Figure. Termination box PDGNTB6
Eaton Predictive Diagnostics RTD6M PD sensor board manual IB07005E Installation procedure IMPORTANT APPLICATION NOTE: USE THE CLOSEST TO A STATOR RTD TERMINATION FOR CONNECTIONS. Long RTD wires (before connections to RTD PD board) introduce significant attenuation for high frequency Partial Discharge signals and also serve as antenna for external noise.. Replace the existing RTD terminal block with the RTD6M PD board. Mounting dimensions of the board are: L*W*H = 7.5 *.05 * 0.8 ; mounting holes have diameter 0.5 for #0 screw at 6.65 distance on the board axis; mounting tabs thickness is 0.5. Be sure you provided a GOOD electrical ground connection at two mounting holes of the board. Use spring washers to improve the connection to ground. If good ground connection through mounting holes is doubtful, run copper braid from both sides tabs of RTD module to the CLOSEST GROUND point in RTD terminating box to ensure good LOW Inductance ground connection. The braid should be about ½ in width and its permissible length should be within 5 (can use 80 AWG wire instead).. If applicable install terminating box with preinstalled six BNC connectors within ~0 ft from the existing RTD terminal box on the motor/generator frame (counting by conduit length). Optimize the location of a terminal box for minimum conduit length and easy access during measurements.. Punch (or drill) a hole in the motor/generator RTD terminal box for a ¾ fitting for solid or flexible conduits. Install a hub. Run conduits to a continuous monitoring device or to the termination box.. If RTD6M PD board is used with a continuous monitoring device additional three wire shielded cable should be used for connection to a spare RTD that not used by customer s temperature monitoring system. This RTD will be used by continuos monitoring system for correlation of PD data to stator temperature. For more details see Manuals for continuos PD monitoring system. 5. Pull coaxial cables (and RTD cable) into the RTD terminal box. Trim cable length, but make sure of extra cable length for easy connections in the RTD terminal box. Coax cables length could be up to 50 depending on device location. 6. Connect RTD wires from a winding to the left side of the board in accordance with the label (see example in Figure ). For two wire RTDs use terminals and, for three wire RTD use terminals, and. For RTD cable shield always use only terminal. In case of four wires RTDs use terminals and for ground/return wires and connect shields with an external jumper. Check connections as described in check procedure. Connect RTD outgoing wires (to a temperature metering system) to corresponding terminals on the right side of the RTD module.
Eaton Predictive Diagnostics RTD6M PD sensor board manual IB07005E Note: If one of RTD wires was solidly grounded in RTD junction box use wire jumpers on RIGHT side of RTD PD module (RTDOUT) to restore ground connections. 7. Route coaxial cables from a PD monitor/termination box to corresponding terminals of RTDPD sensor in RTD junction box. Trim them. The coaxial cable marked as should be routed to the terminals of the board marked as PD and so on. The example of connections is shown on Figure for RTD #0. RTD RTD PD PD Coaxial cable to terminating box Shield RTD To temperature metering device Shield Shield Existing wires from a stator RTD RTD PD PD RTD Existing wires to temperature metering devise EATON CutlerHammer RTD PD Sensor Board Style 50, 6 Channels Made in Mexico RTD5 5 6 PD PD RTD 6 Figure. Example of a circuit with connections to RTD #
Eaton Predictive Diagnostics RTD6M PD sensor board manual IB07005E 8. Prepare RG58 coaxial cables for connection (Figure ). Strip the outer PVC jacket to the distance of ~, unbraid the shield and remove the inner conductor insulation to the distance of ~0., then crimp the blade terminal to the shield, central wire could be terminated to RTD PD board directly without blade terminal. Note: We recommend Vinyl Insulated Blade Terminal by Thomas & Betts, Cat No. TV0BL (Allied Electronics, Catalog 000, p. 6, Stock # 5). We recommend crimp tool CT50H (Allied Electronics, Catalog 000, p. 6, Stock #5). Figure. Coaxial cable preparation 9. Connect coax cables: the central conductor should be connected to terminal, shield to terminal. Push the wires completely into the terminal holes on the terminal board. Tighten the screws. 5
Eaton Predictive Diagnostics RTD6M PD sensor board manual IB07005E Check procedure Use ohmmeter to verify RTDs and coax cable connection.. Integrity of PD measuring circuits could be checked from BNC connectors in a terminating box or from other end of a coax cable at a continuous monitoring device: resistance should be < Ohm;. Integrity of RTD temperature metering circuits could be verified on contacts on right side of an RTD before RTD outgoing wires will be reconnected to RTD PD board: resistance between ground and compensation wires of an RTD (commonly contacts and ) for each RTD should be less than Ohm resistance between signal wire and compensation or ground wires of an RTD (commonly contacts and,) should be ~05 Ohm for copper RTDs and ~000 Ohm for platinum RTDs resistance between RTD shield contact and any of contact,, should be >50kOhm Often, especially in old machines, RTDs can have broken wires. It is still possible to use such RTDs for Partial Discharge measurements, but sensitivity will be lower. It is highly recommended to fill the table below: RTD ## 0 0 0 0 05 06 Resistance between ground and compensation wires (typically contact to ) Resistance between signal and ground wires (typically contact to ) Resistance between signal and compensation wires (typically contact to ) We highly recommend making pictures of RTD PD board and termination box installation. In this case an expert can review the installation and consult for possible corrections. 6
Eaton Predictive Diagnostics RTD6M PD sensor board manual IB07005E Installation Examples Installation of RTD PD sensor board Three wires RTD shielded cables transit through RTD PD sensor board RTD junction box before and after RTD PD Sensor Board installation Termination box is installed on right side of RTD junction box 7