As you know, Dalton Electric does not sell Temperature Controls. But distributors with whom we work do sell them and are in a position to exploit the opportunity of synergistic sales. Our discussion of life factors for a heater will be limited to the effect that different types of control have on the cartridge. The order of controllers will be from most harsh to kindest:
| The analog controller is one that establishes a temperature window and turns the power on at the low limit and turns it off at the upper limit. This is the hardest style of control for a heater as the relay is simply slamming current to the resistance coil. |
 |
|
A proportional control will reduce the heat output gradually as the process approaches the set point temperature and is much kinder to the heater. A PID controller will introduce the integral and derivative action which more capably controls varying loads at set point. In ach controller the ratio of "on" to "off" time changes, adjusting the power delivered to the heater, decreasing stress on the resistance coil and contributing to longer life. |
| Finally, the kindest power input to a cartridge heater is a Variac transformer This device controls the amount of voltage supplied to the heater at a constant level. This reduced continuous supply of voltage will result in the least stress to the heater and result in maximum life. |
 |
Friday Funnies
Normal people believe that if it ain't broke, don't fix it.
Engineers believe that if it ain't broke, it doesn't have enough features yet.
|
