Marsh Bellofram Automatic Timing & Controls Division 304 Series Industrial Percentage Timer - Marsh Bellofram - #1

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800.727.5646 automatictiming.com Automatic Timing & Controls 304 Series Percentage Timer // 304 Series 3 Pe r c e n t a g e T i m er Easily the most rugged and dependable of industrial percentage timers, the ATC 304 incorporates heavy-duty contacts that are capable of switching loads as large as 4.6 KW directly. LARGE CONTACTS: Self-cleaning silver contacts are 3/8 inch in diameter, larger than in any other make of percentage timer. They easily provide 1,000,000 operations at the full rated load of 25 A (non plug-in models). RUGGED AND TROUBLE-FREE: Every component of the 304 has been refined and improved over the years to provide dependable operation for at least 3,000,000 cycles. Its classic simplicity of design makes it virtually trouble-free. CONVENIENT ADJUSTMENT: Graduated in easily read 1% increments, the 304 provides continuous adjustment of on time between 5 and 95%. It also switches the load off continuously when the pointer is set below 3%; and on continuously, when the pointer is set above 98%. The 304 is available in a choice of 15, 30 and 60-second time cycles (60 Hz). Its synchronous motor drives a cam which repeatedly closes the SPST load switch for a percentage of the time cycle, as set on the timer dial, and opens it for the remainder of the cycle. When the dial pointer is set below 3%, the load switch stays open for the full cycle; it remains closed when the pointer is set above 98%. An optional Hold switch also disconnects power to the timer motor when the pointer is set below 3%. Series 304 timers operate continuously and do not reset on power interruption; when power is restored, they resume the interrupted cycle. TYPICAL APPLICATIONS: Ideal for controlling wattage input to electrically heated equipment, the 304 non-plug-in models can pulse loads up to 4.6 KW directly through the SPST load switch; the plug-in models can switch up to 2.3 KW loads directly. The 304 can be used with other types of electrical equipment to control the ratio of on time and off time in a fixed time cycle. In many types of ratio and cascade control systems, the 304 provides rate-of-rise set point drive control; special dial calibrations are available for this application. \\\SPECIFICATIONS MODELS Choice of three: 304E plug-in 304E non-plug-in 304C non-plug-in RANGES Choice of three standard ranges. 15 SEC @ 60 cycles (18 SEC @ 50 cycles) 30 SEC @ 60 cycles (36 SEC @ 50 cycles) 60 SEC @ 60 cycles (72 SEC @ 50 cycles) REPEAT ACCURACY ± 0.1% DIAL CALIBRATION 5 to 95% on time, in 1% graduations. FULL ON, FULL OFF FEATURE. When pointer is set below 3%, load switch contacts are open continuously, above 98%, contacts are closed continuously. HOLD SWITCH (optional). Disconnects power to timer motor when pointer is set below 3%. LOAD SWITCH One SPST (quick make, quick break) switch with self-cleaning heavy-duty silver contacts. CONTACT RATINGS (non-inductive) 304C 25A at 120 VAC 20A at 240 VAC 304E 15A at 120 or 10A at 240V AC–plug–in unit. Non-plug-in unit same as 304C POWER REQUIREMENTS 120 or 240V, 50/60 Hz; 50 mA running current. TERMINALS 4 screw terminals accessible at rear; wiring diagram on housing. TEMPERATURE RATING 32° to 120°F (0 to 50°C) WEIGHT NET: 1 lb., 2 oz. SHIPPING: 1 lb., 7 oz. MOUNTING ACCESSORIES OPTIONAL: NEMA 12 case for 304E, both for surface mounting. \\\OPERATION