Operator`s manual

SCHEMATIC AND WIRING DIAGRAM SYMBOL LEGEND
A – 1a
PUSH BUTTON SWITCH, MOMENTARY, NORMALLY OPEN: A momentary push button switch that CLOSES on activation (makes
contact when pushed) such as the LOW OIL PRESSURE OVERRIDE Switch
PUSH BUTTON SWITCH: A two position push button switch such as the EMERGENCY STOP Switch
PRESSURE SWITCH, MAKES ON RISE: A pressure operated switch that CLOSES (makes contact) on an increase in pressure.
THERMOSTAT, MAKES ON RISE: A temperature operated switch that CLOSES (makes contact) on an increase in temperature
THERMOSTAT, BREAKS ON RISE: A temperature operated switch that OPENS (discontinues contact) on an increase in temperature
GROUND: May be used to show a frame (chassis) ground or a neutral connection.
NORMALLY CLOSED CONTACTS (N.C.): Relay contacts that are SHUT (making contact) when the relay coil is not powered or
energized.
NORMALLY OPEN CONTACTS (N.O.) : Relay contacts that are OPEN (not making contact) when the relay coil is not powered or
energized.
TOGGLE SWITCH: An OFF or ON bat handled switch such as the BURNER switch.
MOMENTARY TOGGLE SWITCH: A bat handled switch that automatically returns to the OFF position when released.
THERMAL FUSE: A fuse, motor overload or other heat reactive protective switch
RESISTIVE LOAD: Relay coils, resistance heaters, resistors.
SNAP DISC, MAKES ON RISE, AUTO RESET: A bi-metal disc that CLOSES a switch should the temperature of the media it is sensing
reach the set point (usually fixed). The Switch will return to its normal position after the temperature drops to a pre-determined level.
SNAP DISC, BREAKS ON RISE, MANUAL RESET: A bi-metal disc that OPENS a switch should the temperature of the media it is
sensing reach the set point (usually fixed). The Switch can be reset only after after the temperature drops to a pre-determined level.
This type of switch is commonly used as a high limit.
SNAP DISC, OPENS ON RISE, AUTO RESET: A bi-metal disc that OPENS a switch should the temperature of the media it is sensing
reach the set point (usually fixed). The Switch will return to its “normal” position after the temperature drops to a pre-determined level.
This type of switch is commonly used as a high limit.
TOGGLE SWITCH, TWO POSITION: An ON – OFF – ON bat handled switch such as the REWIND CLUTCH switch.
© 2006 Ground Heaters, Inc.
V. 2, Rev. 09/01/06