- August 19, 2017
- Posted by: maxpower
- Category: Gear Motors
Following are some Gear Motors Safety Consideration you must follow.
The chance of electric shocks, fires, or explosions can be reduced by giving proper consideration to the use of grounding, thermal and over current protection, type of enclosure, and good maintenance procedures. The following information supplements the foregoing safety considerations: This information is not purported to be all-inclusive and the aforementioned references should be consulted.
- Do not insert objects into the ventilation openings of products.
- Sparking of starting switches in AC motors so equipped, and of brushes in commutator type motors, can be expected during normal operation. In addition, open-type enclosures may eject flame in the event of an insulation failure. Therefore, avoid, protect from, or prevent the presence of flammable or combustible materials in the area of motors/gearmotors.
- Max power gears totally enclosed products are not explosion proof or dust ignition proof nor does Max power gears offer such products for hazardous locations (flammable/explosive gas, vapor, dust). When dealing with hazardous locations, an approved explosive proof or dust ignition proof product is the recommended approach. Exceptions are allowed by the National Electrical Code: The NEC and the NEMA safety standard should be studied thoroughly before exercising this option.
- Open, ventilated motors are suitable for clean, dry locations where cooling air is not restricted, Enclosed motors/gearmotors are suitable for dirty, damp locations. For outdoor use, wash downs, etc., enclosed motors must be protected by a cover while still allowing adequate air flow.
- Moisture will increase the electrical shock hazard of electrical insulation. Therefore, consideration should be given to the avoidance of (or protection from) liquids in the area of motors. Use of totally enclosed motors/gearmotors will reduce the hazard if all openings are sealed.
- Products equipped with thermal protectors are labeled “THERMALLY PROTECTED.” If severe over-loading, jamming, or other abnormal operating conditions occur, such heat sensitive protectors operate to open the electric power supply circuit. Motors/gearmotors with “automatic” thermal protectors MUST NOT be used where automatic restarting of the drive unit could be hazardous in that clothing or parts of the human body could be in electrical or physical contact with a machine that starts unexpectedly when the thermal protector cools down. MANUAL RESET protectors or suitable electric supply disconnect devices/procedures should be used where such hazards could be created.
- The windings of DC stepper motors, or their switching transistors, must be disconnected from the DC power source to avoid unexpected motion. If not, extraneous signals could turn on the power transistors and generate motion.
- Some oil-type capacitors contain a nonPCB impregnate which is flammable. Such capacitors are identified by means of a Warning Label and, in addition, are stamped “NON-PCB.” The user has to provide at least .57 in. (14.5 mm) clearance beyond the terminal blades for case expansion to allow an internal safety switch to permanently open and electrically disconnect the capacitor. The internal pressure sensitive switch is designed to prevent the expulsion of the flammable dielectric medium if excessive temperatures are generated by electrical operation. Do not discard such capacitors into open fire as excessive internal heat could cause them to explode.
- Motors/gearmotors which employ capacitors can develop more than nameplate voltage across the capacitor and/or capacitor winding (depending on design). Also, overdrive voltages may be many times greater than a stepper motor’s continuous voltage rating. Suitable precautions should be taken when applying such motors.
- Abnormal conditions, such as cut-out switch failure, or a partial winding failure, can very occasionally cause some AC motors/gearmotors to start in a direction reverse from normal. Also, use of a capacitance or resistance value other than that recommended for Hy-Sync™ motors may result in unpredictable reverse operation. Susceptibility to unplanned reversing under such conditions is greatest when the motor’s actual load is light relative to its rated load. One-way clutches or similar devices are advisable if unexpected reverse rotation is unsafe in the application.
- Do not rely upon self-locking gears or permanent magnet, stepper, Hy-Sync™, or energized motors to hold a load in place if movement could result in personal injury. Mechanical locking devices should be used in such applications.
- For motors driven by electronic controls, do not use a function of the control for safety interlock purposes. An independent switch or relay should be used. On stepper motors, the device should be between the control and the motor.