Zero Speed Switch
Zero Speed Switch / Electronic Speed Switch / Monitor / Indicator
Now a days in material handling plants under/Over speed monitor is one of the essential control and safety device.
Electronic Speed Monitor is used to monitor speed of conveyors, crushers, rolling mills, agitators, mixers, stirrers, screw conveyors, and other industrial machinery. This device actuates relay contacts at preset speed. Using these contacts desired control action such as zero speed protection / under speed protection/ over speed protection can be achieved.
- It Senses speed by non – contact way. Hence no moving parts.
- No wear and tears of rollers or misalignment of couplings. Easy speed setting.
- Built-in initial bypass time delay arrangement.
- Speed setting possible from 1 RPM to 5000 RPM in optional ranges.
- The totally enclosed sensor works in the presence of dust, dirt water, oil & chemicals.
- Direction sensing and speed monitoring of various locations from a single point is possible.
- Intrinsically Safe Sensors and speed switches with Flameproof Enclosures are available for use in Hazardous area.
The basic principle of speed monitor is comparison of pulses received from sensor with standard pulses. The unit consists of two parts : CONTROL UNIT and “SENSOR PROBE”. The sensor is to be installed with its sensing face in close proximity of rotating object. On this object, flags are to be fixed. The sensor products strong electromagnetic waves, which get disturbed by the flags, giving rise to corresponding pulses. These pulses are fed to the control unit where they are compared with standard pulses to sense the speed.
The control unit incorporates an output relay. This relay will operate at preset speed giving 2C/O contacts of 5 Amp 240 VAC resistive.
Initial Time Delay & Nuisance Delay :
Initial time delay facility to allow the rotating mechanism to attend the desired speed is provided. Standard delay is 0-30sec. Nuisance delay allows the system to delayed the trip action for few seconds as it may recover the speed.
The sensor is epoxy potted and housed in metallic/ plastic tube. Control unit is enclosed cast AL / DMC enclosure.
Common Specification :
Totally enclosed, Inductive Type
Enclosure : Ni – Cr plated Brass enclosure, M 30 size with two check nuts (Refer group 4 of ordering proforma for other options)
Control Unit :
- Enclosure : Field mounting IP65, Cast AL/Din Rail IP30 / Flame Proof (Refer group 2 of ordering proforma)
- Output : 2 C/O relay contact, Rating 5Amp resistive at 230V AC with Led indication for supply ON, Sensor ON and Relay ON
Electronic Speed Switch / Zero Under Speed Switch :
The model is provided with the potentiometric setting. Suitable speed range is to be selected from six optional speed ranges 1 – 10, 10 – 100. 5 – 50, 50 – 500, 100 – 1000 and 500 – 5000 RPM. It also has a special optional facility to multiply speed range X 10 & X 100. Easy speed setting by the potentiometer, with supply ON ‘Relay ON’ and ‘SENSOR LED’ indication.
- Speed Switch : Din Rail mounting, IP 30 panel mounting enclosure, potentiometric setting, type ESW – D
- Speed Switch : Weatherproof, field mounting, IP65 enclosure, potentiometric setting, type ESW – F
- Speed Switch : Weatherproof, field mounting IP65 enclosure, DMC Enclosure potentiometric setting, type ESW – M
- Speed Switch : Flame – proof enclosure for use in hazardous area with intrinsically safe sensor and control circuit, type ESW – L
Micro Controller Based, Speed Indicator Monitor – Tachometer Series ESW M
Micro Controller based circuitry packed with customer friendly features.
- Selectable number of flags. Enter number of flags which are available at site, Speed Monitor will get automatically calibrated for these flags
- Digital Display
- Adjustable trip delay
- Settable hysteresis
- Special models for combined under over speed monitoring duty
- Special models with RS 232 / RS 485 retransmission facility
Digital Tachometer Series : ESW – D
It receives input from Transducer ( like proximity switch ) or analog input ( from transmitter ) and indicate speed in RPM, MPM or any other unit. Rotational/linear speed indication is possible. The unit is enclosed in panel mounting ( cutout 92 X 92 ) or dust proof, field mounting or flame proof enclosure.
Frequently asked questions
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.