Fully interlocked voice warning system that announces conveyor startup 30 seconds before the motor energises. Mandatory under the Mines Act 1952 and state factory rules. MT-PSH based.
A conveyor belt that starts without warning is one of the most common sources of serious injury in Indian factories and mines. Workers clearing a blockage near the tail drum, walking across a transfer point, or adjusting a tracking roller can be caught by a belt that starts without notice. The Mines Act 1952 makes pre-start warning mandatory for conveyors in mining operations. Most state factory rules extend this requirement to manufacturing facilities.
Under the Mines Act 1952 and Coal Mines Regulations, no belt conveyor shall be started until an audible pre-start warning has sounded for a sufficient period to allow all persons to move clear. Most state factory rules and internal HSE standards extend this to 30 seconds minimum. The warning must be interlocked with the motor start circuit — the motor must not be able to start until the warning sequence has completed.
A single hooter at the head end is insufficient for conveyors longer than 50m. Workers at the tail drum or intermediate transfer points may not hear a single-point warning clearly. For conveyors over 50m, install MT-PSH units at the head end, tail end, and any transfer station — all triggered simultaneously from the same PLC output. The 30-second sequence plays at all points before any motor is permitted to start.
| Parameter | Specification |
|---|---|
| Pre-warning duration | 30 seconds (configurable 10–60 seconds) |
| Motor interlock | Relay output on message completion — N.O. contact rated 5A 230V AC |
| Output | 110–120 dB at 1m (horn speaker directed along conveyor run) |
| Trigger input | Dry contact from PLC DO or start pushbutton |
| Power supply | 230V AC standard; 24V DC on request |
| Message language | Hindi + regional language (bilingual, sequential). Custom messages included. |
| Enclosure | IP55, suitable for outdoor conveyor gallery mounting |
| Compliance | Mines Act 1952, Coal Mines Regulations, state factory rules |
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