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TECHNICAL TRAINING

Warming up With Watts

By: Donald Dougherty, Senior Technician

This month, we’ll be discussing the various electric heating devices
installed on our machines and how to get the most out of them.
Electric heaters are rated in watts, which is a unit of power flow.
It is a product of Voltage times Current. Watts are typically used to
describe the dissipation of power.
A common type of electric heater is the “resistive” type. A house-
hold toaster is an example of a resistive electric heater. When elec-
tric current passes through a resistive wire, the moving electrons
cause friction, producing heat. This is like rubbing your hands to-
gether briskly to warm them up.

The heaters on Loram machines are of the resistive type. These include the water and hydraulic tank heaters, en-
gine block heaters, generator, cab, tool room space heaters and heat tape.
Safety: Because current and voltage measurements are taken on live circuits, remember to observe all Arc-
Flash safety procedures and wear Appropriate PPE while working on live electrical equipment!
Troubleshooting these circuits is a bit different because instead of shorting out and tripping the circuit breaker,
the common failure of heating elements is for them to “open circuit” instead.

This is where an amp clamp meter comes in handy for troubleshooting. Let’s say you suspect a hydraulic tank
heater is not working because the oil temperature is at or below the ambient outside temperature. (In this case
the temperature switch setpoint is 70 degrees F.)

Continued Pg. 17

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