reduce costs and improve control with enviro-tec® ssr based, time ...
reduce costs and improve control with enviro-tec® ssr based, time ...
reduce costs and improve control with enviro-tec® ssr based, time ...
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<strong>time</strong>s larger than the older devices<strong>with</strong> equal current ratios, <strong>and</strong>heat dissipating areas over twenty<strong>time</strong>s the size of the olderdevices. The latest versions ofSSR’s feature three phase, 480volt <strong>control</strong> in a single package,greatly reducing the number ofconnections required, whichfurther enhances reliability.Another advantage of the SSR iszero voltage switching. In otherwords, the power to the heater isonly switched on <strong>and</strong> off when theAC waveform is crossing zerovolts.This switching method not onlygreatly <strong>reduce</strong>s stress on systemcomponents, it also avoids voltagetransients which are generatedwhen the power is switched on oroff at the peak of the AC voltage.Most older <strong>time</strong> proportioned<strong>control</strong>s, <strong>and</strong> many current ones,do not use this switching method.DOES TIME PROPORTIONEDHEAT REDUCE COSTS ANDIMPROVE CONTROL?With only a limited number ofsteps of electric heat, chances arethat the heating requirements ata given point in <strong>time</strong> will notmatch the incremental capacity ofthe number of stages available. Forinstance, in the case of a twostep heater, if the actual outputrequirement of the heater is sixtypercent, the second stage willneed to be switched on (onehundred percent output) <strong>and</strong> off(fifty percent output) in an effortto maintain the desired temperature<strong>control</strong>. Consequently, thespace or discharge temperature(depending on the heater application)is mostly either too warmor too cool. Not only is energywasted when the space is toowarm, but, since it takes moreenergy to heat a space to a desiredtemperature than to maintain itat the temperature, energy iswasted when the space is reheatedafter cooling. This energy losscan be <strong>reduce</strong>d by switching thesteps on <strong>and</strong> off more rapidly,but, as discussed early, this <strong>reduce</strong>sthe life of the system components.Also, occupants may findthe “clicking” associated <strong>with</strong>energizing <strong>and</strong> de-energizingmagnetic contactors annoying.VERTICAL HI-RISE FAN COIL ELECTRIC HEATElectric heat is available in a wide variety of kW<strong>and</strong> voltage configurations. Options include doorinterlock disconnects <strong>and</strong> low voltage <strong>control</strong>s.Controls <strong>and</strong> electric heat components on allENVIRO-TEC ® products are factory mounted <strong>and</strong>wired, <strong>and</strong> ETL listed as an assembly.DIRECT DRIVE BLOWER COIL ELECTRIC HEATPremium quality materials such as stainless steelelement hardware, Ni-Chrome wire elements, <strong>and</strong>high temperature rated wiring exceed typicalindustry quality st<strong>and</strong>ards. Control <strong>and</strong> electricheat configurations on all ENVIRO-TEC ® productsare <strong>with</strong> single point power <strong>and</strong> are ETL listed asan assembly.Specifier’s Guide Volume 1 • ©2003 Environmental Technologies, Inc.
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