8
4. Pump runs but does not pump
down the wet well.
a.
On three phase only,
pump rotation may be wrong.
Wiring of pump to con trol
pan
el may be re
verse
sequenced.
b. Impeller may be dragging
in volute due to sol
ids.
High am per age draw would
identify this.
c. Refer to the pump manual for
other possibilities such as closed
discharge gate valve, etc.
5. Severe humming/chat ter ing of
contactors and control relays.
a. There may be low voltage.
Check voltage at primary
and secondary of control
transformer us
ing a
volt me ter. This low voltage
condition may cause severe
chat ter ing and burnout of
contactors and relays.
b. Contactor may have dust
around magnet of coil
struc
ture. Dry or clean
as re quired.
c.
Check voltage to the
control panel. Contactors
require a minimum of
85% of full volt age to pull
in without chatter. If the
problem is a re
cur
ring
one, measure voltage with
recorder on a 24 hour basis.
d. Make sure the floats are
locat
ed away from any
turbu lence.
e. Dry out the junction box
(if furnished); moisture
in the junction box may
cause relays to energize
intermittent ly.
6. Short cycling pump.
a. Check float controls.
7. Run light stays on.
a. Selector switch may be in the
Hand position.
8.
Nuisance tripping of
over load on motor starters or
cir cuit break ers.
a. Check pump amp draw with
amp probe and compare to
nameplate amps on pump.
b. The impeller may be locked
up due to excessive debris or
solids.
c. Possible motor failure (fault in
windings).
d. Pump may be miswired to
ter mi nal block.
e.
Voltage and current
unbalance. Three phase
only. Voltage un bal ance on
three phase power sources
can cause motor current to
become un bal anced and
exces
sive heating will
re
sult. Trip
ping of the
over
load protectors and
premature motor failures
can be expected if the
current unbalance exceeds
five percent.
Percent Maximum Current
Current = Difference from x 100
Unbalance Average Current
_______________
Average Current
To determine if motor current
un bal ance is a function of the motor
or the power supply:
1.
Label the leads and the
ter mi nals 1, 2, and 3 respectively.
2. Record the amperage for each lead.
3. Move each lead to the next
terminal (1 to 2, 2 to 3,
3 to 1).
4. Again read the amperage of
each lead.
5. Move each lead to the next terminal
(1 to 3, 2 to 1, 3 to 2).
6. Again read the amperage of
each lead.
7. If the unbalance moves with
the motor leads, the un balance
is caused by the mo
tor. If
the unbalance remains with the
terminals, the un bal ance is in
the pow er supply.
8. If the current unbalance exceeds
five percent, nui sance tripping or
ex ces sive heating will result.
9. Connect leads for the lowest
percent of current un bal ance.
f.
Connections and start
components. Single phase
only.
1. Disconnect all power from
the panel before making
these checks.
2. Motor winding re sis tance
read ings.
a.
Disconnect all three
motor leads from panel
terminal blocks.
b. Using a volt-ohmmeter, with
the scale set on RX1, measure
the resistance be tween the
leads with the chart.
Typical
Motor Resistance
Winding Leads Reading
Main
Black to
Lowest
White
Start
Black to
Next
Red Lowest
(Middle)
Both
White to
Highest
Red
(Main & Start)
Pump
Troubleshooting