CN1566, CN2086, CN2586, CN3086, CN3586, CN4086 and CN5086 Electric Motors Caterpillar

Thermal Performance Problem

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Table 1
Thermal Performance Open Air Cooling System
Experienced Malfunction		Possible Cause		Corrective Action
High Winding Temperature	High Cooling Air Temperature	Possible Cause		Corrective Action
Yes	Yes	High intake air temperature	Ambient temperature	Add ventilation to decrease ambient temperature
Yes	Yes		Exiting air is pulled back in	Ensure sufficient clear distances surrounding the machine
Yes	Yes		Heat source nearby	Place heat sources further away, check ventilation
Yes	Yes	Faulty air flow	Dirty machine interior	Clean machine parts and air gaps
Yes	Yes		Faulty cooling arrangement	Inspect cooling arrangement condition and correct assembly
Yes	Yes		Air intakes are blocked	Clear air intakes of debris
Yes	Yes		Air filter is clogged	Clean or replace air filters
Yes	Yes	Damaged cooling fans		Replace fans
Yes	No	Overload	Control system setting	Check machine controls, eliminate overload
Yes	Yes	Overspeed		Check actual speed and speed recommendations
Yes	No	Network unbalance		Check measurements, sensors, and wiring
Yes	Yes	Faulty instrumentation or measurement system		Check measurements, sensors, and wiring
Yes	No	Winding fault		Check windings

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Table 2
Thermal Performance Air-to-Air Cooling System
Experienced Malfunction		Possible Cause		Corrective Action
High Winding Temperature	High Cooling Air Temperature	Possible Cause		Corrective Action
Yes	Yes	Low primary cooling circuit performance	Damaged cooling fan	Replace fan
Yes	Yes		Fan rotating in wrong direction	Replace fan
Yes	Yes		Dirty machine interior	Clean machine parts and air gaps
Yes	Yes	Low secondary cooling circuit performance	Damaged external fan	Replace fan
Yes	Yes		Fan rotating in wrong direction	Change shaft-mounted fan or correct external blower motor operation
Yes	Yes		Leaking cooler	Repair cooler
Yes	Yes	High intake air temperature	Ambient temperature too high	Add ventilation to decrease ambient temperature
Yes	Yes		Exiting air is pulled back in	Ensure sufficient clear distances surrounding the machine
Yes	Yes		Heat source nearby	Place heat sources further away, check ventilation
Yes	No	Overload	Control system setting	Check machine controls, eliminate overload
Yes	Yes	Overspeed		Check actual speed and speed recommendations
Yes	No	Network unbalance		Check measurements, sensors, and wiring
Yes	Yes	Faulty instrumentation or measurement system		Check measurements, sensors, and wiring
Yes	No	Too many starts		Let the machine cool down before restarting
Yes	No	Winding fault		Check windings

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Table 3
Thermal Performance Air-to-Water Cooling System
Experienced Malfunction			Possible Cause		Corrective Action
High Winding Temperature	High Cooling Air Temperature	Water Leakage Alarm	Possible Cause		Corrective Action
Yes	Yes	No	Low primary cooling circuit performance	Damaged cooling fan	Replace fan
Yes	Yes	No		Fan rotating in wrong direction	Change shaft-mounted fan or correct external blower motor operation
Yes	Yes	No		Dirty machine interior	Clean machine parts and air gaps
Yes	Yes	No	Low secondary cooling circuit performance	Coolant pipes are blocked	Open cooler and clean pipes
Yes	Yes	No		Faulty coolant pump	Check and repair the pump
Yes	Yes	No		Faulty flow regulator settings	Check and adjust coolant flow
Yes	Yes	Yes		Leaking cooler header	Replace the cooler header
Yes	Yes	No		Air inside the cooler	Bleed the cooler through bleeder screw
Yes	Yes	No		Emergency cooling hatch open	Close the emergency cooling hatch tightly
Yes	Yes	No	Cooling water inlet temperature too high		Adjust cooling water temperature
Yes	No	No	Overload	Control system setting	Check machine controls, eliminate overload
Yes	No	No	Network unbalance		Check that the network balance fulfills requirements
Yes	Yes	Yes	Faulty instrumentation or measurement system		Check measurements, sensors, and wiring
Yes	No	No	Too many starts		Let the machine cool down before restarting
Yes	No	No	Winding fault		Check windings

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Table 4
Thermal Performance Rib-Cooled
Experienced Malfunction	Possible Cause		Corrective Action
High Winding Temperature	Possible Cause		Corrective Action
Yes	Overload	Control system setting	Check machine controls, eliminate overload
Yes	Overspeed		Check actual speed and speed recommendations
Yes	Network unbalance		Check that network balance fulfills requirements
Yes	Faulty instrumentation or measurement system		Check measurements, sensors, and wiring
Yes	Too many starts		Let the machine cool down before restarting
Yes	Winding fault		Check windings
Yes	Dirty machine exterior		Clean machine exterior
Yes	Air flow is reduced		Remove obstacles. Ensure sufficient air flow

There are two fundamental reasons that might cause an increase in the temperature of the machine:

The effect of the cooling system has declined
The machine is producing an excessive amount of heat

If the machine temperature exceeds the normal values, measures should be taken to determine which cause is dominant in a particular incident.

Note: An excessive heat production might be caused by a winding problem or by network unbalance. In these cases, corrective actions on the cooling system would be ineffective or harmful.

If the winding or cooling air temperature detectors show an abnormal temperature, check the cooling system. Two separate maintenance issues affect the cooling system. The air or water flow through the heat exchanger, if equipped, must also be checked.

Ensure good air circulation in the primary cooling circuit inside the machine. This task can be fulfilled by cleaning and checking the machine interior during overhauls or if problems arise.

Check the air or water flow through the heat exchanger. If the cooler is equipped with an external blower fan, check the operation of the fan. Ensure good air circulation in the primary cooling circuit inside the machine. Clean and check the machine interior during overhauls or if problems arise.

Other possible causes for poor cooling performance might include elevated ambient temperature, high intake air or water temperature, and low air or water flow. Poor cooling performance can be caused by operating at excessive altitudes and high relative humidity. These environments affect the amount of air per volume.

In addition, lubrication or bearing malfunction might lead to high bearing temperature. A seemingly high temperature might also be caused by a temperature measurement system malfunction. Refer to the "Resistance Temperature Detector Problem" section for more information.