| 摘要 |
<p>An adjustable heater for aquaria, comprising a substantially tubular container ( 2 ) within which are housed an electrical heating element ( 3 ), a switch ( 6 ) comprising s fixed contacts ( 7, 8 ) and moving contacts ( 9, 10 ) and capable of electrically connecting the heating element ( 3 ) with an external source (R) of electrical power, a temperature sensor ( 12 ) with a bi-metal strip ( 13 ) capable of detecting the temperature of the liquid and interacting with the switch ( 6 ) to move it from a closed position to an open position when a predetermined temperature (T) is to reached. The moving contacts ( 9, 10 ) of the switch ( 6 ) are secured to a free end ( 13 '') of the bi-metal strip ( 13 ) while the other end ( 13 '') of the bi-metal strip ( 13 ) is electrically insulated. This yields the advantage that electrical current does not pass through the bi-metal strip ( 13 ) and therefore does not create a Joule effect within it which affects the sensitivity and proper behavior of the temperature Is sensor ( 12 ).</p> |
