TM5-6115-593-34NAVFAC P-8-631-34TO-35C2-3-463-2Figure 5-20. Under and Overfrequency Devices, Test Setuplight control film (6) on the front of the panel usingscrews (1).(5)Mount the digital clock (7) using screws (1).(6)Connect lead wires and remove tags.5-11. ALARM HORN.a.Removal. Remove alarm horn (18, figure 5-1)as follows:WARNINGBEFORE STARTING ANYMAINTENANCE PROCEDURE, SETMAINTENANCE LOCKOUT SWITCHTO LOCKOUT. DISCONNECTNEGATIVE CABLE FROMBATTERIES. REMOVE EXTERNALPOWER BY OPENING CB101(EXTERNAL POWER CIRCUITBREAKER) AND DISCONNECTINGPOWER CABLE FROM RECEPTACLEJ101 (120V RECEPTACLE).(1)Tag and disconnect wires to alarm horn.(2)Remove horn (18) by removing screw (15),washer (16), and lockwasher (17).b.Test. Connect 24V DC across terminals 1 and 2of alarm horn. If horn does not sound, it isdefective and should be replaced.c.Installation.(1)Install horn (18) using screw (15), washer (16),and lockwasher (17).(2)Connect wires and remove tags.5-12. RELAYS MOUNTED ON REAR PANEL OFCONTROL CUBICLE (54, figure 5-1).a.Underfrequency relay 81GU (9, figure 5-19).(1)Test the underfrequency relay by connectingas shown in figure 5-20.(a)Switch S1 closed.(b)Adjust variable frequency generator for 50Hz output.(c)With ohmmeterconnected betweenterminals 5 and 7, adjust frequencygenerator to 48.5 Hz. Relay should trip asfrequency is decreased. Ohmmeter will nolonger show continuity.5-25
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