THERMAL OVERLOAD RELAYS
1- LST THERMAL OVERLOAD RELAYS
➣ OVERVIEW
(1) Connection for mounting onto contactors
(2) Selector switch for manual/automatic RESET and RESET button
(3) Switch position indicator and TEST function of the wiring
(4) Motor current setting
(5) STOP button
(6) Transparent, sealable cover Secures the motor current setting
(7) Supply terminals
➣ BASIC FUNCTIONS:
• The LST thermal overload relays are designed for:
• Inverse-time delayed protection of loads from overloading
• Inverse-time delayed protection of loads from phase failure
• TRIP CLASSES
The LST thermal overload relays are available for normal starting conditions with trip class 10.
• PHASE FAILURE PROTECTION
The LST thermal overload relays are fitted with phase failure sensitivity in order to minimize temperature rises of the load
in the case of a phase failure during single-phase operation.
• SETTING
The LST thermal overload relays are set to the rated motor current by means of a rotary knob. The scale of the rotary
knob is shown in ampere.
• MANUAL AND AUTOMATIC RESET
Automatic and manual reset is selected by pressing and turning the blue button (RESET button).
• RECOVERY TIME
After tripping due to overload, the LST thermal overload relays require some time until the bimetal strips have cooled
down
• TEST FUNCTION
The TEST slide can be used to check whether the operational LST thermal overload relay is working properly
• STOP FUNCTION
If the STOP button is pressed, the NC contact is opened
• AUXILIARY CONTACTS
The LST thermal overload relays are fitted with an NO contact for the "tripped" signal, and an NC contact for
disconnecting the contactor.
➣ TYPE: LSTD / LST0 / LST2 / LST3
➣ APPLICATIONS:
• System protection: The units are responsible in the main circuit for overload protection of the assigned electrical loads
(e.g. motors), feeder cable and other switching and protection devices in the respective load feeder
• Motor protection
• Alternating current, 3-phase
• Alternating current, 1-phase
• DC current
➣ SIZE OF CONTACTOR :S00, S0, S2, S3
• SIZE S00 up to 12A
• SIZE S0 up to 25A
• SIZE S2 up to 50A
• SIZE S3 up to 100A
➣ RATED OPERATIONAL VOLTAGE: Ue 690/1000 VAC
➣ RATED FREQUENCY :50/60 Hz
➣ TRIP CLASS: Class 10
➣ THERMAL OVERLOAD RELEASE
• LSTD integrated 0.11 … 12 A
• LST0 integrated 1.8 … 25 A
• LST2 integrated 5.5 … 50 A
• LST3 integrated 18 … 100 A
2- LA THERMAL OVERLOAD RELAYS FOR MINIATUR POWER CONTACTORS
• With hand reset
• Thermal overload release( 0,12- 14)A
