Emco EE301-T, Manual

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Step-9 : Vary the PT I/P to more than 132V (OV level), then the OV indication
alongwith ‘L’ indication should come. Decrease the voltage below
127V then OV command goes “off”. However ‘L’ command remains
“ON”. Decrease PT I/P voltage slightly less than 112V, ‘L’ will go
off. This is Bandwidth condition. Decrease PT I/P slightly less than
108V, ‘R’ indication should come. If the UV/OV, L & R indications are
coming as above that means Display PCB is OK.
Step-10 : Set Time Delay (TD) control to 30 sec. Vary the PT I/P to get ‘L’
condition. Measure time from which ‘L’ indication comes to the time
‘LR’ indication comes. The ‘LR’ indication will remain ‘ON’ for 2 sec.
after which once again ‘TD’ is initiated. (The ‘TD’ indication is
provided on Main PCB). If time delay is not ok, it means Main
PCB or TD pot is faulty. Replace the faulty component. If ‘LR’ & ‘RR’
indications are not coming after set time delay then IC4 on Main PCB is
faulty.
(In above description, it is assumed that display & LEDs are OK).
Step 11 : To check relay, vary PT I/P to get ’L & R’ conditions in Normal mode &
confirm that Lower relay and Raise relay are operating, by checking
continuity at rear terminals. If “RR” & “LR” indication are coming but
relays are not operating then check 12V supply to relay on Main PCB or
check Test / Normal switch S2. If relays are operating but 'NO’ contacts
are not closing means relay contacts are faulty. Ensure that Relay
contacts are not connected to the Tap-Changer. Replace Main PCB.
Step-12 : To check TPI PCB, connect Resistor chain between Max. & Min. &
wiper to Common. Measure approx. +1V on the IC2 pin 36 with DMM.
Adjust pot P5 to get +1V.
Measure the step voltage across individual
resistor. It should be 100 ± 3mV. If not then adjust pot P2 to get 100 ±
3mV. If the voltage does not come then IC3 may be faulty. If the voltage
is OK but still the display does not read properly, then IC2 on the TPI
PCB may be faulty. Check TPI displays 88 in "Test" mode. If not then
"Test / Normal" switch is faulty.
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