Hobart Brothers 6910, Operation And Maintenance Manual With Illustrated Parts List

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4. Transformer-Rectifier Operation
(Optional Equipment) (See Fig. 5)
Transformer-Rectifier operating instructions are contained in its operating manual, however some gener-
ator set instructions are required here.
A. Direct Current Power Delivery
NOTE: If the customer adds a Transformer-Rectifier to a standard machine which was
NOT
equipped
with a T-R when it left the factory, he must remove the jumper lead which will be found on the small
terminal strip in the generator set voltage regulator (see 1-1; 19, Fig. 12). If your generator set has a
factory installed T-R, the jumper will have been removed.
(1) When delivering power from a T-R, prepare the generator set for DC power delivery the same as
for AC delivery, except do not connect AC output cable and do not close AC load contactor
(see Para.
2, D and E ).
(2) For T-R operating instructions, see Hobart Manual No. OM-433.
B. Simultaneous 28.5-V DC and 115-V AC Power Delivery
If both 28.5-V DC and 115-V AC must be delivered at the same time, the following rules and precau-
tions must be observed.
(1) Place T-R current limiting switch in OFF position. This will eliminate the soft start feature of the T-
R, but will prevent AC voltage from dropping low enough to trip the AC load contactor.
(2) Line-drop compensation on the T-R must be REDUCED or turned DOWN completely to prevent
opening of the AC load contactor by an overvoltage condition. Readjust T-R line-drop compensation
so that AC voltage
(as indicated by the generator set voltmeter) does not exceed 118-V AC when the
DC load is 500 Amperes. If higher DC voltage is needed, adjust T-R line-drop compensation as re-
quired.Observe AC voltage while making this adjustment to be certain that it does not go TOO HIGH
with DC load.
NOTE: Voltage will be controlled on the AC/400Hz output, therefore, the DC output will be unregulated.
(3) During simultaneous, continuous operation, loads on either circuit are limited only by the capaci-
ties of their respective circuits, however, the combined loads should not exceed the rated capacity of
the generator set
(90 KVA or 72 KW).
(4) If a controlled DC output condition is required, place the T-R current limiting switch in the ON posi-
tion or with the line-drop compensator rheostat adjusted up. Make certain that the load on the T-R
does not exceed 200 amperes DC while the generator set is also delivering AC power to a load. If, un-
der these conditions, the load on the T-R exceeds 200 amperes, a potential problem may develop
wherein the AC output may change to compensate for the added DC load and thus shut the AC out-
put off due to an overvoltage or undervoltage condition.
NOTE: Voltage will be controlled on the DC output, therefore, the AC output will be unregulated if the
DC load exceeds 200 amperes.
OM-2028
August 31/90 Revised 1-3
Page 9