Liberty Pumps Engineered Pump Systems (EPS) - Manual (Page 8)

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5) Check that control fuse is not blown
Control panels will usually have circuit breakers or other overload protection to protect a pump from burning itself
out from overdrawing current. Similar to this, the control circuit has its own built in protection in the form of a fuse.
Usually there will be two circuits, one for control power and one for alarm power. Each will have its own fuse that
would blow under a high amperage condition. If power is not reaching the control circuitry, it is possible that the
control power fuse has blown and would need to be changed. To check the fuse, there is plastic fuse holder that
needs to be loosened and then pulled out. Turn this knob counterclockwise to loosen and pull the fuse holder out.
If the fuse has blown, it will appear blackened and burnt. For the user’s convenience, the control panels are
equipped with replacement fuses of the correct size on the inside of the front door.
Problems Exclusive to 3 Phase Systems:
1) Check for rotation on 3-phase pumps
Three phase power uses three separate alternating currents that peak at different integrals. With pumps that are
powered by three phase electric, the phase sequence of the motor must match the phase sequence of the power
source. When the sequences match, the pump will operate properly. However, when the phases are out of
order the pump will run backwards (i.e. the impeller will rotate in the wrong direction). This will cause an extreme
loss of performance and could raise the amps drawn by the pumps. To ensure that the power to the pump is
installed correctly, always check the rotation of the pump before lowering it into the pit. The correct rotation is
shown below for a grinder and sewage pump (Figure B). If the pumps are rotating in the wrong direction, turn off
the power and reverse any two leads. This will reverse the phase sequence and will correct the pump rotation.
2) Check overloads for tripping in 3-phase panel
All the three phase panels have overload protection included inside the control panel enclosure, usually located
directly adjacent to the motor contactors. These switches are set for a certain amp rating based on the pump
being used. The switches are in the horizontal position when tripped (off). To reset the switch, turn the knob
clockwise into a vertical position. Please note that the switches come in “off” position. They must be reset during
installation to be able to supply power to the pumps.
3) Check overload amp level in 3-phase panel
All the three phase panels have overload protection included inside the control panel enclosure, usually located
directly adjacent to the motor contactors. These switches are set for a certain amp rating based on the pump
being used. Underneath a clear screen on the overload, there is a dial which represents the amp level that
overloads are set to. This amp level should represent the Full-load amps (FLA) of the pump being connected to
the control panel. To check that the amp level is correct look at the tags located on your pumps. There will be a
FLA listed on the tag. The setting on the overload should be set at least this high, and could be set as much as
10% or 1 amp higher, whichever is greater. Not having this set correctly could result in nuisance tripping of the
overload which would not allow the pump to operate.
4) Confirm that transformer connections were made
Our three phase panels power the controls through a transformer that will accept three phase power, and convert
it to 120 V, single phase for control power. All of our three phase panels are designed to be able to run on 208 V,
240 V, and 480 V three phase electric, and thus an adjustable transformer is required. To accommodate each
different voltage, there is a lead to the primary voltage tap to the transformer that needs to be connected. The
lead will come with a label to instruct which terminal to connect to, based on which voltage is being used. If this
lead is not connected, the transformer will not deliver power to the controls of the panel and the panel will not be
able to operate the pumps. If this lead is incorrectly connected, the control panel circuits could be damaged.