Safety Switches

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.

application of zero speed switch:

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.

advantages:

• 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 by-pass time delay arrangement.

• speed setting possible from 1 rpm to 5000 rpm in optional ranges.

• totally enclosed sensor, works in presence of dust, dirt water, oil & chemicals.

• direction sensing and speed monitoring of various locations from single point is possible.

• intrinsically safe sensors and speed switches with flameproof enclosures are available for use in hazardous area.

operation:

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.

output:

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 .

enclosure:

the sensor is epoxy potted and housed in metallic/ plastic tube. Control unit is enclosed cast al/dmc enclosure/din rail plastic enclosure.

commen specifications:

sensor probe:

totally enclosed, inductive type

enclosure: ni-cr plated brass enclosure, m 30 size with two check nuts( for other refer oredering info)

control unit:

enclosure: field mounting ip65, cast al/din rail ip30/ flame proof

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:

series esw

the model is provided with 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 500-5000rpm.

it also has a special optional facility to multiply speed range x 10 & x 100. Easy speed setting by potentiometer, with supply on `relay on’ and `sensor led’ indication.

models:

• 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 

Chute block switch:

tilt switch

application:

tilt switch is an electronic device specially developed for sensing the level of an approaching stockpile on stacker-reclaimed or material in a hopper, in a silo and to provide an output signal which can be used to initiate control actions

advantages:

·        the sensor probe of the unit has omni directional sensing pattern and hence on whichever side it tilts, it definitely provides an output signal.

·        tilt switch has in built adjustable on and off delays to take care of the nuisance tripping due to wind flow or momentary jerks at the start and stop of the machine.

construction:

the tilt switch comprises of two parts, viz. Sensor probe and monitoring unit. The sensor probe is of tubular structure and is hanged by means of a chain link arrangement. When the tilt probe gets tilted by material the output relay gets actuated.

Pull- cord switch

Features:

• Universal (common) cast aluminum/ DMC enclosure.
• Same overall and general mounting dimensions and hence reduction in variety of mounting brackets.
• Rationalized design and construction allows inter changeability of parts.
• Special rubber seal (0 ring) on shaft for better protection against ingress of dust, dirt etc.

Standard specifications:

Enclosure: weatherproof, field mounding type, IP 65 cast AL/ cast iron, epoxy painted, colour light gray

DMC (FRP) enclosure for use in corrosive environment.

Special flame proof enclosure for use in hazardous area, group LLA, LLB, LLC

Output contacts: 1no + 1no/ 2no + 2 NC

Contact rating for standard models: 16amp resistive at 440VAC

Contact rating for models with reed switch contact: 30VA, 24 VDC/ 230V AC, 1 AMP. (please specify your control voltage)

Reset: pull cord switch: manual reset type

Belt sway switch: auto reset type

Optional accessories:

• Separate junction box for termination of cables  
• Indicating lamp: long life led indicating lamp for indication of operated pull cord switch 
• Mechanical flag indication for pull cord switch 
• Separate reset lever 
• Communication card (for trip indicator) 
• Hermitically sealed reed contacts for use in extreme dusty and corrosive conditions 

Pullcord switch series: PSW

Application:

Pull cord switch also known as rope operated emergency switch is used as a safety switch to stop the conveyor belt in case of an emergency.

Construction:

Pull cord switch is housed in dust and weatherproof enclosure with ip65 grade of protection. Study and heavy-duty cam-switch with robust contacts is used to give longer service life. Operating handle fitted with spring steel rings at both ends for fixing the rope. The design of the rings gives maximum flexibility in operating condition. Enclosure is epoxy painted to give high corrosion resistance. The switch is designed with manual reset type of mechanism.

Operation:

Pull cord switch is mounted on the walkway side of the conveyor belt, preferably at about every 20 meters. When the rope is pulled from any side. The switch is operated . Unless and until the handle is reset to normal position manually, the switch remains in operated condition.

Pullcord wire and tying accessories :

Pull cord wire, Dia. Aprox. 5-6 mm, 6x7 construction, galvanized steel wire with PVC cover. Specially extruded for material handling industry.

Tying clips, cable guide, eye bolt, tension spring, cable gland  for tying pull cord cable to individual switch are also supplied  at extra cost.

Belt -sway switch

Features:

• Universal (common) cast aluminium/ dmc enclosure.
• Same overall and general mounting dimensions and hence reduction in variety of mounting brackets.
• Rationalized design and construction allows inter changeability of parts.
• Special rubber seal (0 ring) on shaft for better protection against ingress of dust, dirt etc.

Standard specifications:

Enclosure: weatherproof, field mounding type, ip65 cast al/ cast iron, epoxy painted, colour light gray

Dmc (frp) enclosure for use in corrosive environment.

Special flame proof enclosure for use in hazardous area, group lla, llb, llc

Output contacts: 1no + 1no/ 2no + 2 nc

Contact rating for standard models: 16amp resistive at 440vac

Contact rating for models with reed switch contact: 30va, 24 vdc/ 230v ac, 1 amp. (please specify your control voltage)

Reset: Pull cord switch: manual reset type

            Belt sway switch: auto reset type

Optional accessories:

• Separate junction box for termination of cables
• Indicating lamp: long life led indicating lamp for indication of operated pull cord switch
• Mechanical flag indication for pull cord switch
• Separate reset lever
• Communication card (for trip indicator)
• Hermitically sealed reed contacts for use in extreme dusty and corrosive conditions

Belt-sway switch series: bsw

Application:

The switch allows smooth running of the conveyor and protects it from damages by over swaying which can occur due to uneven loading of material, worn out idler roller bearings etc.

Construction:

The switch is housed in dust and weatherproof enclosure with ip65 grade of protection. The contact roller is supported on poly plastic bearing (delrin) having high relativity of lubrications and the lowest coefficient of friction. This assures smooth operation of the roller over a long period of the time. Roller mechanism is of self reset type. The enclosure is epoxy painted to withstand harsh climate.

Operation:

 For normal running of the belt with acceptable swaying, the belt-sway switch is generally mounted on both sides and near the edge of the conveyor belt. A is generally mounted on the both sides and near the edge of the conveyor belt. A small clearance is allowed between contact roller and the belt edge to allow the normal running of the belt with acceptable swaying. When swaying exceeds normal limit, the belt edge pushes the contact roller, which drives the switch and operates the contacts. The switch reset automatically when the belt resumes normal running.