Maintenance 75

Low voltage disconnect

The LVD voltage adjustment levels should be verified periodically (preferably at intervals no greater than one year). Refer to the “Fault diagnosis” section found at the end of this chapter for the verification procedure. When the verification has been completed, set the Test/Bypass switch to the Normal position.

The DC connections on the main contactor should be tightened with a torque wrench set at 70 in.-lb. periodically (at one-year intervals) to avoid the build up of hot spots and voltage drops.

Troubleshooting

Rectifier fail alarm

Verify that the input AC voltage is within the specified limits.

Cycle the AC breaker off/on to reset the unit from a possible HVSD shutdown.

Make sure the HVSD potentiometer is adjusted properly. Refer to the “Start- up procedure” section of the “Installation and start-up procedure” chapter of this manual for the adjustment procedure.

If the unit is used in parallel with other units the rectifier may indicate an RFA alarm when the unit produces no current (see Note below). This could mean that the float voltage is too low. Increase the float voltage by turning the FLT potentiometer clockwise until the ON/RFA led turns green.

Note: Triggers an alarm at no load condition, only for the following releases, or under.

NT5C06BB,BB-1,BB-3,BCRel.10

NT5C06CA,CA-1,CA-3,CA-5,CC Rel.10

NT5C06CB,CB-1,CB-3,CDRel.12

NT5CO6CE-61(-46)Rel.12

-Verify the front panel inrush current fuse (F1, 3/4 A, 250 V). A blown fuse on the MPR15E (NT5C06CB/CD/CE) may indicate that the input line voltage is too high. Refer to “Appendix C: Recommended replacement parts” to order a replacement fuse.

-The unit must not be opened for on-site servicing. If a problem persists contact your local Astec representative.

25A Switch Mode RectifierNT5C06B / C Installation and User Manual

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Emerson MPR25, MPR15 Series user manual Low voltage disconnect, Troubleshooting Rectifier fail alarm

MPR15 Series, MPR25 specifications

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