Medium Power Supply Protector


Our Medium Power Supply Protector provides protection for AC/DC power supplies used to power motors and motor controllers. We offer both a small version and a medium version, from Robot Power, one of the best robot power supply manufacturers in the business. The function of the PS Protector family of products is to protect robot power supplies from reverse current flows generated by electric motor Back-EMF.

Battery power supplies can generally just absorb a brief amount of reverse current without issues, but our Medium Power Supply Protector shields your motors from damage due to this phenomenon.


2 in stock (can be backordered)

SKU: rp-ps-protector-med Categories: , , ,


Medium Power Supply Protector Inline:

  • Voltage: 6V – 48V
  • Current: 20A-30A continuous, 60A peak
  • Size: 2.95″ x 1.35″ x .55
  • Weight: 14g
  • Ideal Diode function
  • Reverse current flow protection
  • Reverse input polarity protection
  • Inductive kickback spike protection
  • Optional plastic enclosure

How the Medium Power Supply Protector works.

Back EMF:

Due to the nature of electric motors, a rotating motor generates a voltage of reverse polarity to the voltage applied by the driving motor controller. If this “Back-EMF” voltage is higher than that applied to the motor by the motor controller it can cause a reverse current flow from the motor to the power supply. The most common scenario for this to occur is when the motor is operating near full speed and the motor controller rapidly commands a lower power level. At full speed, the motor is generating Back-EMF nearly equal to the power supply voltage minus losses such as the load and friction.

Sudden voltage drop:

When a sudden lower voltage is applied to the rotating motor by the motor controller the driving voltage seen by the motor is reduced before the mechanical motor rotation can catch up. This leaves the motor generating the Back-EMF of its current rotation speed while the driving voltage from the motor controller is at a lower level. This causes current to flow from the higher voltage potential generated by the motor to the lower applied by the motor controller i.e. back from the motor into the motor controller and hence back into the power supply.

Voltage Spike:

Due to the nature of the output regulation circuits in the vast majority of AC/DC power supplies, attempted reverse current flow causes the power supply to increase its output voltage to maintain current flow out of the power supply. The resulting voltage spike may be large enough to exceed the maximum ratings of voltage-sensitive circuits such as the power supply output regulation circuit or the motor controller circuits. This can lead to the destruction of the power supply or the motor controller or both.

Ideal Diode and MOSFET Protection:

The PS Protector family acts as an “Ideal Diode” by using a low-resistance MOSFET to pass current in the forward direction with very low losses but to instantly (a few nanoseconds) switch off the MOSFET to block reverse current. As soon as the output voltage level is lower than its input the Medium Power Supply Protector turns the MOSFET on to allow normal current flow again.

Allows Multiple Power Supplies:

A second function of the Medium Power Supply Protector is to allow multiple power supplies or battery supplies to power a load or for multiple loads to use one power supply without interfering with each other. Scenarios such as hot-swapping batteries or power supplies or seamless failover are also supported by the PS Protector.

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