applications benefits converter selection
poor performance installation warning
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Maxiphase CONVERTERS are designed to operate one or a combination of three phase motors from single phase power. Selection of correct converter is determined by converter specification charts under products.

Uses include...
• Woodworking Machinery • Printing Presses • Pumps • Elevators • Sewing Machinery • CNC Applications • Sewage Processors • Welders, Forklift Chargers • Hoists and Cranes • Grain Drying Operations • Air Conditioning Systems • Dry-cleaning Equipment • Metal Working Machinery • Food Processing Equipment • Recycling Operations • Egg Packers & Handling Systems

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Maxiphase CONVERTERS offer ...

• Quick startup, with low inrush amperage, using electrolytic start capacitors with a positive mechanical centrifugal switch.

• Standard duty Lo-VOLTAGE models for 230 volt applications.

• CNC models for computerized machinery applications.

• Standard duty Hi-VOLTAGE models for agricultural irrigation systems and other 460 volt applications.

• 1 Year Warranty


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* Selecting a converter model is similar to selecting transformer kVA sizes. Both starting and running loads must be considered, especially starting loads because amperages are always higher to start. Maxiphase converters offer only one duty rating per model. There are not heavy or super-heavy duty ratings, even though heavy and super-heavy duty needs are found in load applications. Whenever those conditions are present, simply choose one size larger converter for heavy duty needs or double sizes for super-heavy duty (such as, punch presses, direct drive centrifugal blowers, etc.)

* Total combined horsepower ratings on all converters are general ratings. Many applications will have motors operating in varied stages of load conditions (such as metal or woodworking machinery, etc.) from no load to full load. This nameplate rating which is three times the largest horsepower rating of the converter gives a general performance rating.

* In applications which have multiple motors operating continuously at full load use a .66 multiplier to calculate total combined horsepower capacity. For example, an RPC 5-15 has a combined horsepower rating of 15hp. When motors are running continuously in a full load condition, (such as refrigeration compressors, pumps, etc.) multiply 15hp x .66, which results in a combined total horsepower capacity of 9.90 or 10hp for the RPC 5-15 converter.

* Air conditioning and refrigeration units are commonly underrated in horsepower. For example, a refrigeration compressor motor rated at 7.5hp may have a full load amp rating of 33 amps at 230 volts. An amp load of 33 amps at 230 volts is the equivalent of a 12-13 horsepower motor. In that case an RPC 15-45 converter should be used. Always check amp draw and load conditions before making a selection! It is also recommended after true HP is determined to use the next larger HP converter due to high starting current.

* Due to higher starting currents, 3450 RPM motor applications may require the next larger rating converter. For example, a 7.5hp 3450 RPM motor on a wood molder which has heavy cutter heads, may require an RPC 10-30 converter. A safe rule is that 3450 RPM motors require the next larger model converter.

* If two or more motors start simultaneously, the combined total horsepower of those motors would be considered the largest motor horsepower on the converter specification chart. For example, one 1hp and one 2hp motor starting simultaneously would equal one 3hp motor. In this case an RPC 3-9 would be the correct converter to use. NOTE: This applies only when motors start at the same time!

* A Rotary Phase Converter must be started before the load is applied. Starting a converter with the load applied can cause winding failure in the rotary converter.

* For resistive loads (such as heating elements) determine the input amperage and compare it to an equivalent motor horsepower amp draw. For example, a resistive load of 18 amps would be between the amp draw of a 5hp and a 7.5hp motor. Since it is greater than a 5hp and less than a 7.5hp, an RPC 7.5-20 would be the correct converter. A resistive load of 22 amps would be the maximum load for an RPC 7.5-20 converter. No other load could be applied at the same time.

* Transformer loads (such as battery chargers, welders, etc.) are calculated by converting the primary amperage of the welder or charger to an equivalent motor horsepower amperage. For example, a charger with a primary amperage of 26 amps would be similar to a 10hp motor which has an amperage of 28. However, you may multiply the charger amperage by .60 which in this case gives a result of 15.6 amps. This is the equivalent of a 5hp 230 volt 3 phase motor. The correct converter would be an RPC 5-15.

* For operation of 460 volt machinery from a 230 volt 1 phase source, use a step-up transformer between the 230 volt phase converter and the 460 volt application. An alternative is to use a step-up transformer before the converter and choose a 460 volt phase converter.

* For extremely hard starting or inertial load applications (such as metal shears, punch presses, some compactors, etc.) choose a converter model which is double the largest motor horsepower rating. For example, a metal cutting shears with a large flywheel and a 5hp drive motor, would require an RPC 10-30 converters.

* For CNC and other computerized applications use CNC model converters.

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1. Power service is too light. For example, attempting to start a 15hp motor (using an RPC 15-45 converter) off a 100 amp electrical service could cause the single phase input voltage to drop below 200 volts. Consequently, the motor would not be able to reach full speed.

2. Improper converter selection. If load is extremely hard to start or motor is 3450 RPM, converter selection should have been oversized by one or even two sizes. It is very important to gather as much detail on application before sizing converter. Proper sizing gives reliable performance.

3. Connecting manufactured phase (T3) to magnetic controls. Never connect control circuits or computerized circuits to manufactured phase (T3). Fluctuating voltage on the manufactured phase (T3) due to varying load can cause magnetic starters and contractors to open or damage computerized controls, if manufactured phase is supplying power to control circuits. Remedy: connect control circuits to converter terminals (T1) and (T2) which are the 230 volt single phase input terminals. This assures a solid and steady voltage to contractor coil or other control devices.

* CAUTION: Automatic equipment (such as air compressors) must be turned off before starting phase converter. An alternative is to install an automatic-start phase converter that is started by the pressure switch of the air compressor (or other application) after which a delay relay starts the load, in this example an air compressor.

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1. Single phase lines L1 and L2 shall be connected to rotary converter through appropriate switch or definite purpose conductor. Attach line wires L1 and L2 to converter terminal board as shown on connection diagram.

2. Three phase output wires are attached to terminals T1, T2 and T3 provided on converter terminal board as shown on connection diagram. Three phase output can be connected to load through fused safety switch or breaker panel before distribution to various three phase motors. Local electrical codes may apply.

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1. Never connect (T3) manufactured phase to magnetic control circuits, computerized control circuits or any single phase application. Fluctuating voltages will cause unsatisfactory operation or may damage such applications.

2. Phase converter must be started before load is applied. Starting converter with load switched on may prevent converter from reaching full speed resulting in blown electrolytic capacitors or damaged converter winding.


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Maxiphase, All rights reserved.