COLDWATER LAKE FACILITIES
DUPLEX PUMP STATION
TROUBLESHOOTING GUIDE
REFERENCE: Operation Instructions
Ladder Schematic Diagrams
SCOPE
The following troubleshooting guide has been specifically prepared for this system. It
primarily relates to electrical failure. When problems develop a good troubleshooting
technique is most important. The following guide will not cover all circumstances.
Many mechanical functions are beyond the scope of this guide. Mechanical functions
should be dealt with by people knowledgeable of the equipment. A pump overload can
be caused by mechanical problems relating to the pump and motor such as bearings,
foreign material in pump binding seals, misalignment, etc.
1.0 GENERAL
1.1 ORGANIZATION
The troubleshooting guide format is arranged in three general areas:
1- A discussion of common problems
2- A discussion of problem isolation techniques
3- A list of symptoms with associated possible causes
In most cases identification of the cause will result in obvious corrective action.
1.2 SUGGESTIONS
Any changes that may be associated with a problem can be very helpful. Any unusual
noise, smell vibration, etc., may give a good clue as to the ultimate cause. A routine
inspection of the panel to look for any changes should be conducted. Look for: noise,
humming, excessive dust, discoloration, smoke, burning smell, disconnected wires,
vibration, chattering, heat, burning, extra loose screws, other loose parts, etc.
A most useful test on an energized system is to check for the presence of power directly
on a suspected component.
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On a de-energized system test the suspected components with an ohmmeter to determine
that the resistance is in expected range.
1.3 ADJUSTMENT
Do not touch or adjust anything without being sure you know what you are doing. All
adjustable components have either been factory set or set upon first start-up. A change
that requires field readjustment is unusual. If a change is made care should be exercised
that the original settings are noted. Original settings can thereby be re-established if
necessary.
1.4 SAFETY
The electrical energy levels present in the circuits of this system during normal operation
are potentially very dangerous, do not take any chances. When working on the
equipment assume that all electrical parts are energized. Even though all direct
connections normally supplying power to a panel are broken some parts may still be
"HOT". All work involving entry into an electrical panel should only be accomplished
by a knowledgeable technician. Check for foreign voltages on outgoing terminals.
2.0 COMMON PROBLEMS
2.1 MOTOR OVERLOAD
Cause may be electrical or mechanical. Possible mechanical problems could include:
contamination or failure of bearings, fouling of motor shaft or impeller, broken or
plugged pipe, etc. Possible electrical problems could include: shorted turns in motor
windings. unusually high voltage, unusually low voltage, bad electrical connection, etc.
If the motor overload/breaker trip light has come on try resetting the motor starter
overload and try again to run the motor. A second overload trip should be investigated
before resetting. If resetting the motor starter overload does not allow the motor to start
probable cause is the motor circuit protector trip. See the following paragraph.
2.2 MOTOR CIRCUIT PROTECTOR (MCP) TRIP
Most MCP trips are caused by winding insulation failure in the motor. If possible,
inspect the motor before resetting and attempting to run again. Persistent "nuisance"
tripping indicates a problem in the system, too low a setting on the MCP trip point, or
insufficiently large heater in the starter. Refer to the catalog section of this manual to
understand the method of setting the MCP trip point and to compare motor amps to
heater size.
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2.3 INPUT SWITCH FAILURE
The action of the input switches may be simulated with test switches. If operation is not
normal (see operation instructions) check input switches with the test switches as
follows:
1- A switch that should be closed, but is not, can be tested by moving the test
switch to "C". If the desired function takes place, this indicates an input switch
has failed. If not, a problem in the panel may be indicated.
2- A switch that should be opened by is not, can be tested by moving the test
switch to "O". If the desired function takes place, this indicates an input
switch failure or water in the wiring. If not, a problem in the panel may be
indicated, If water in the wiring is suspected, see paragraph 2.4 following.
3- Normal function test. Sequential operation of the test switches can be used to
simulate complete system automatic cycling.
4- Be sure to return test switches to the proper position after testing, Normally,
the switches should be in "A". There are cases where either the "O" or "C"
position may be desired for abnormal conditions.
2.4 DESENSITIZING D.C. RELAYS FOR LEAKAGE
A relay may have to be desensitized due to leakage from a leaky cable. If water gets into
wiring of a remote switch, leakage resistance may occur causing the switch to always
appear closed to the controls. A sensitive D.C. relay, such as the Midtex 611 series used
on this panel, can be adjusted to still work by adding a resistor in parallel with the coil of
the relay. A resistor is needed if the relay will not turn off when the float switches are
open. Voltage measurements should be made with a digital voltmeter with 10
MEGOHM input impedance.
1- Make sure contacts in the relay circuit are open.
2- Measure voltage across pins 8 to B on the relay socket. If the voltage is greater
than 1.0 volts a resistor is required to desensitize the relay.
Example: Voltage measured is 6 volts. Graph says a 6K ohm resistor is
required. Use a resistor 1/2 that of size indicated, 3K ohm. Do not use below
2K ohm if graph indicated less than 4K ohm is required.
3- Install the resistor between pins 8 and B on relay socket.
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If the contacts are open, re measure voltage across pins 8 and B. Voltage should be less
than 1.0 volts. If not, use the next smaller size resistor until voltage is less than 1.0 volts
when float switches are on open circuit.
For probes, the procedure is the same as for float switches except that when probes are in
the water, the voltage across pins 8 and B must be a least 3.0 volts to operate reliably.
Voltage should be less than 1 volt when probes are out of the water.
3.0 PROBLEM ISOLATION
This system has been provided with specific alarm indicator lights to indicate expected
common problems. The labels on the alarm lights are generally self-explanatory and
should lead you directly to easy correction of the problem. For example, if the overload
indicator light goes on, a correction can probably be accomplished by resetting the motor
overload or the motor circuit protector.
The detailed isolation of a problem can also be associated with the general area of power
supply within the panel. Control power is available at 120 volts AC, 24 volts AC, and 24
volts DC. There is a higher voltage AC power available to run the motors. Note that
although a problem may be isolated to one of the areas of power, some components may
cause problems that are involved with more than one section. For example, relay R1 is in
the DC control voltage circuit, but has operating contacts in the AC circuitry.
There are four types of plug-in relays used in this system: 24 volt DC relays with 11 pin
square sockets, 24 volt AC relays with 11 pin round sockets, a 24 volt AC alternating
relay with 8 pin round socket, and a adjustable voltage monitoring relay in the 115 volt
range with an 8 pin round socket. Relays that are alike may be swapped in order to help
troubleshoot.
A malfunction that appears associated with a given function can be tested by swapping
it's relay with another identical relay. If the malfunction follows the relay the apparent
cause is a problem with the relay. For help in determining what relays to try swapping
refer to the ladder schematic diagram. Also refer to the schematic diagram to understand
the function of the test switches. There is a test switch at each input switch so that the
operation can be completely checked as though all the input switches were operating.
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4.0 SYMPTOMS AND POSSIBLE CAUSES
SYMPTOM
POSSIBLE CAUSE
Continuous signal that an input
input switch is closed.
Test switch in "O".
Water in wiring.
Faulty input switch.
Continuous signal that an
input switch is open.
Test switch in "C".
Broken wire.
Faulty input switch.
Pumps will not run in AUTO.
Open float circuit.
R1, R6, R7, RA, OL1, OL2
Tripped circuit breaker.
MCP's.
Power input.
All lights out.
Power input.
Tripped circuit breakers.
GFI.
General alarm lights ON,
Horn switch ON, horn not
sounding.
DC power supply malfunction.
CB3.
PB1A
R5.
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