ABOUT TECH RESOURCES WHERE TO BUY CONTACT ENGLISH∨ Entire Site CARTRIDGES MANIFOLDS ELECTRONICS SOLUTIONS ACCESSORIES Home » About » Precise electro-proportional inverse relief valve Precise electro-proportional pressure relief perfect for fan drive motor control New RPEI provides smooth, precise control of fan speed with full-flow relief to protect the system if the fan motor stalls. The RPEI combines an electro-proportional adjustable pilot stage and high-capacity main stage to provide precise pressure control inversely proportional to the input electrical current. The pressure setting at zero current is also manually adjustable to allow the system designer to fine tune the RPEI to their specific system requirements. In fan drive applications, the RPEI electro-proportional inverse relief valve delivers smooth, precise changes in pressure to the fan drive motor to maintain the desired fan speed while also acting as a full flow relief valve for system safety in the event the fan motor stalls. The RPEI defaults to the maximum pressure setting to ensure the fan drive continues to cool in the event of electrical power or signal loss to the XMD driver or valve coil. Features of the new RPEI include the following: 25 gpm (95 L/min) flow capacity Available in two nominal-pressure settings: "A" range - 3000 psi (210 bar). Manually adjustable from 900 to 3000 psi (60 to 210 bar). Requires 740 Series low-power coil. "W" range - 5000 psi (350 bar). Manually adjustable from 2000 to 5000 psi (140 to 350 bar). Requires 740 Series high-power coil. Designed and tested to 5 million on-off operational cycles Exceeds new NFPA test standard T2.6.1 R2014 for fatigue and burst pressure ratings Standard zinc-nickel plating for 1000-hour salt fog protection Fully compatible with Sun's XMD valve drivers for applications requiring closed-loop control Below are three examples of standard circuits for hydraulic fan drive control; two circuits using the single-valve electro-proportional RPEI relief and one featuring a popular two-valve alternative – the RBAN inverse-acting pilot valve with the RPEC main stage valve. Both approaches ensure that the fan drive will continue to cool in the event of loss of electrical power or signal. Unidirectional fan drive control In the first example, this unidirectional fan drive control circuit uses the RBAN inverse-acting pilot valve with the RPEC main stage valve to ensure the fan drive continues to cool in the event of electrical power or signal loss to the XMD driver or valve coil. The RPEC delivers smooth, precise changes in pressure to the fan drive motor to maintain the desired fan speed while also acting as a full flow relief valve for system safety in the event the fan motor stalls. This cartridge-to-cartridge arrangement can be simplified using the new RPEI. Bidirectional fan drive control This bidirectional fan drive uses the new RPEI and adds a controlled fan reversing function using a Sun directional control valve. For harsh, dirty on- and off-road environments, fan direction can be changed at defined periods to blow debris or purge the radiator or heat exchanger to restore cooling efficiency and air flow. As with the unidirectional circuit, the RPEI provides electro-proportional relief for motor safety as well as the modulated pressure for a given command to match fan speed with cooling demands. The RPEI ensures the fan continues to operate if there is a loss of electrical signal. Priority flow and secondary fan drive control This expanded solution consists of an integrated package with Sun’s LHFA priority bypass compensator valve and its own RDBA relief valve to provide an adjustable load-sense relief limiting the maximum working pressure of the priority flow. The remaining flow is diverted to the cooling circuit for on-demand cooling. This circuit gives the system designer a highly functional, compact solution that can be adapted easily for use in multiple applications in any market. These solutions rely on the RPEI electro-proportional relief valve to provide the motor safety relief function along with modulated flow and pressure for a given command to match fan speed with cooling needs. Get help with your next application When you're ready to design the RPEI into your next application, reach out to your local Sun Hydraulics distributor for help with solutions designed specifically for you. Find your local Sun distributor here. 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