PULL CORD SWITCH
1] How far apart are emergency stop button on a conveyor?
ANS: Pull cord switch should be placed at every 25 Mtr on both side of conveyor, with necessary supports to rope. These supports are either of I bolt or Cable carrier at turning or change in level of the conveyor.
2] How does an emergency Pull cord switch work?
ANS: Pull cord switch is mounted on the walkway side of the conveyor, Pull cord rope is attached to operating lever in such a way that it can be operated from both side. Typical Arrangement is shown in the below diagram. Various accessories are required for its proper function depending on-site condition.
3] How are Pull cord switch Wired?
ANS: Safe way of wire Pull cord switch is through NC contact. All Pull cord `s NC contact is connected in a series further interlock to turn OFF the Conveyor ( Motor)
BELT – SWAY SWITCH
1] What is belt sway switch?
Ans: Belt sway switch is heavy-duty field mounted protective switch Used to detect sway or deviation in belt due to overload or tear in Bellator misalignment.
2] How does belt sway switch work?
Ans: Belt sway switch is mounted in such a way that roller position of Belt sway switch( belt alignment switch) will come in an acceptable range Of deviation. If the deviation exceeds the belt pushes the roller and Contact inside switch gets change. This change in contact is used for Further interlock
ZERO SPEED SWITCH
1] What is the use of Zero speed switch?
Ans: Zero speed switch is used to detect the speed of driven part ( Tail side of Pulley )of the system has become zero or lower than the set speed to stop the driver ( Motor ).
2] What is working principle of Zero speed switch?
Ans: ZSS consist of 2 part , sensor probe and control unit.
The metal piece/ flag is fixed with the rotating shaft in such a way that it rotates in front of the sensor probe. These pulses generated are fed to control unit where they are compared with set rpm (set pulses ), If pulses fed by sensor probe is below set PPR or RPM then the output of control unit changes. Usually, the output is potential-free relay contact.
This relay contact is further used to trip the motor or for corrective action.
3] What is zero speed switch and how to use a zero speed switch?
Ans: Zero speed switch is a combination of a sensor probe and a control unit. sensor probe detects the motion of the shaft connected to the motor and fed to the control unit. The control unit compares the frequency of fuse with set frequency (RPM). If it is lower than the set rpm control unit changes relay status and this relay is further used to control the motor on-off signal.