Product Manual

11
properly installed and grounded in accordance with
all local codes and ordinances. Do not modify the
plug – if it will not fit the outlet, have the proper
outlet installed by a qualified electrician.
Improper connection of the equipment-grounding
conductor can result in a risk of electric shock. The
conductor with insulation having an outer surface
that is green with or without yellow stripes is the
equipment-grounding connector.
If repair or replacement of the electric cord or plug
is necessary, do not connect the equipment-
grounding conductor to a live terminal.
Check with a qualified electrician or service
personnel if the grounding instructions are not
completely understood, or if in doubt as to whether
the tool is properly grounded.
Repair or replace damaged or worn cord
immediately.
11.2 Variable frequency drive
The inverter is not user-
serviceable. Any programming or service must
be performed by qualified personnel.
The inverter contains high
voltage elements that may retain a significant
charge for several minutes after power is shut
off.
This hoist uses Variable Frequency Drive, also
called an A.C. Inverter, to provide infinitely variable
speeds within the specified range. The inverter
controls motor speed by varying the frequency of
voltage supplied to the motor. This is especially
useful for slowing a load as it nears drop point.
The inverter does not require any programming; it
has been pre-programmed from the factory. With
the possible exception of the reset button, the
buttons on the face of the inverter should never
be pushed at any time. Use only the controls on
the pendant cord.
If you suspect a problem with the inverter or its
settings, contact JET technical service at 1-800-
274-6848.
A lightning strike or power
surge may cause inverter failure. When hoist is
not in use, disconnect power plug, or have a 3-
or 4-pole disconnect installed on the power
side.
11.3 Inspecting hoist motion
1. Before closing circuit breaker and testing hoist,
check that wiring has been complete. If hoist
cannot be observed when circuit breaker is
closed, station an observer within sight of hoist
to report any movement when power is
applied. Be prepared to disconnect power if
hoist motor starts when power is applied – the
hoist must remain motionless when power is
applied. Find and correct any problems before
continuing.
2. With no load on load hook, press UP button
very briefly and observe hoist action. The hook
should move upward.
3. On hoists with 3-Phase power supply, if the
hook moves in opposite direction to that shown
on control button, or if no motion occurs when
UP button is pressed, then the power supply
wires are incorrectly positioned.
Disconnect hoist from power, and switch
any two of the three supply wires at the power
source (excluding the ground wire). Do not
attempt to rewire the hoist circuit or
pendant controls for this problem. Use the
same safety precautions when reversing two
of the supply wires as was used when the
wires were originally connected.
4. Reconnect power and test hoist movement
again without load. Run hoist to maximum
lifting height to ensure lift limiting devices are
operating properly. Adjust speed knob
throughout its range to test variable speed
function.
12.0 Pre-operation inspection
12.1 Inspecting load chain
Clean chain with non-acidic solution, and carefully
inspect entire load chain. Replace damaged chain
before using hoist. See section 17.2 for maximum
pitch allowed for chain length. If the chain exceeds
this amount, it must be replaced.
Also replace the load chain if any of the following
are identified:
1. Seriously rusted or cracked.
2. Marks on the chain surface are deeper than
5% of the link’s diameter.
3. Links are twisted or deformed.
4. Links are stretched too long or considerably
worn on the surface, especially at points where
links contact each other.
Never extend load chain by welding a second
piece to the original.
Do not operate hoist with
twisted, kinked or damaged load chain. Do not
splice load chain.
Check that chain does not twist along its length
from hoist to hook. If twist is present on units with
multiple falls, the hook has been capsized; it must
be passed back through the chain loop to remove
all twist in the chain.