U.S. TSUBAKI SHOCK RELAY
TSB151, TSB152 Shock Relay for Overload Protection
ACTUAL LOAD METER Actual current of the motor is indicated in percentages, which makes it easy to set “LOAD CURRENT,” regardless of the value of the actual current load. LOAD CURRENT This presets the load current at the optimum setting in the range from 30% to 130% of the motor’s current. When the actual load current exceeds the preset current for the preset SHOCK TIME, the SHOCK RELAY trips to break the motor circuit. Audible alarm devices or warning lamps may be installed if desired. The LOAD CURRENT should be preset by observing the ACTUAL LOAD METER condition because the motor generally runs under its rated current value. FINE ADJUSTMENT Adjustment is preset at the factory. When fine adjustment of actual load current is required, this may be used to adjust from –5% to +30% of the indicated meter value. START TIME When starting a motor, the starting current value is greater than the running current. This starting current value continues until the motor reaches normal speed. During this starting period, the time of which mainly depends on the type of load, the function of detecting the overload current is disabled. Adjustable range is from 0.2 to 20 seconds.
TERMINALS FOR CONNECTION All terminals are located on the upper surface to provide easy access. POWER INDICATOR Indicates that the power supply is on. TRIP INDICATOR Lamp comes on when SHOCK RELAY trips. TEST BUTTON This switch is used to verify SHOCK RELAY operation. RESET BUTTON (manual) Reset can be done quickly whenever a cycle restart is desired. SHOCK TIME This presets the overload period. Range is vari- able from 0.2 to 3 seconds. Every momentary load over the preset current with a shorter peri- od than the preset period is ignored. When the overload equals the preset period, the SHOCK RELAY will trip immediately to break the power supply to the motor.
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U.S. Tsubaki SHOCK RELAY monitors the change in motor current that closely approximates the torque output of the motor. Should the motor current exceed the preset LOAD CURRENT point for a preset length of SHOCK TIME (continuous overload time), the SHOCK RELAY will shut down the motor power supply.
DIAGRAM OF OPERATION
TYPICAL CONNECTING DIAGRAM
TSB151, TSB152
M Motor MC Electromagnetic Contactor TH Thermal Overload Relay CB Circuit Breaker
Note: Refer to Specifications on page D-15.
D-7
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