Under Frequency Protective Device Test

CHAPTER 17 KIT AND OPTIONAL EQUIPMENT REPAIR INSTRUCTIONS

TM-5-6115-545-34 Generator Set Diesel Engine Driven Tactical Skid Mtd. 30 Kw 3 Phase 4 Wire 120/208 and 240/416 Volts Manual
Page Navigation
338

available to the operator, specifically adjustments to the voltage or frequency adjust devices. On gen- erator sets utilizing a droop-type speed control system as the prime speed control, the speed and droop portions of the control may be adjusted. No other adjustments to the voltage and frequency con- trol systems shall be made. Adjustments to the load, voltage or frequency controls shall be re- corded on both the data sheet and recording chart(s). Stabilization will be considered to have occurred when four consecutive voltage and current recordings of the exciter field either remain unchanged or have only minor variations about an equilibrium condition with no evident continued increase or decrease in value after the last adjustment to the load, voltage or fre- quency has been made. (b) Perform this test using resistive load only. Remove reactive load after stabilization. (c) For sets with droop-type governors: 1. Load the set to 125% of rated load. Adjust the frequency to the rated value and maintain the load for 5 minutes. (d) For generator sets with isochronous- type governors, repeat step (c) above but do not ad- just the frequency. (e) Results. Compare these results with the requirement of Table 16-1. 16-25. Under Frequency Protective Device Test. a. General. For generators that power certain types of equipment, it is extremely important that the circuit interrupter open when the frequency fails appreciably below rated value. Severe damage may otherwise result to the powered equipment. To insure that the circuit interrupter will open at or before the critical frequency value, the generators are equip- ped with an underfrequency protective device. The device on this generator operates electrically. Al- though the under frequency protective device must be capable of functioning at any voltage throughout the specified voltage operating range, it is necessary only to perform the test at the specified maximum, at rated, and at minimum voltage limits. b. Apparatus. Instrumentation for measuring load conditions shall be as described and illustrated in method 205.1, paragraph 205.1.10 of MIL-HDBK-705. c. Procedure. (1) Preparation For Test. Connect a voltmeter and frequency meter to the generator set terminals, ahead of the circuit interrupter, and the remainder of the apparatus as shown in the applicable figure of paragraph 205.1.10 of MIL-HDBK-705. (2) Test. (a) Operate the generator at rated speed and voltage, and at no load since the generator is equipped with an electrical-type underfrequency protective de- vice, this test shall be repeated with the voltage ad- justed to maximum and minimum voltage for the speci- fied voltage operating range. (b) With the circuit interrupter closed, slowly decrease the operating speed until the protective de- vice causes the circuit interrupter to open. The elec- tric governor must be deactivated to sufficiently de- crease the speed on Class 1, precise sets. (c) Record the speed. (d) Repeat the test while rapidly decreasing the operating speed. Again record the speed. (e) Operate the generator at rated speed and voltage, and at rated load. (f) Repeat steps (b), (c) and (d). d. Results. Compare the test value of frequency with that given Table 16-1. 16-14

Privacy Statement
Press Release
Contact