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RV Power Management Systems

Last Changed 3/23/2009

RV park electricity is a commodity that quite often does not meet necessary standards.  Your RV has several electrical and electronic devices that can be damaged by bad power.  It is wise to protect your RV with a power management system.

The things to check the park power post for:
  • The voltage present (too low <104 volts?  too high > 132 volts?)
  • a good ground
  • a good neutral
  • the line frequency (60 Hz?)
Power Management We have a Good Governor, that in the past, we used to test park power before we connected the RV power cord.  We did not have the adapter to test both legs of the 50 amp outlet but we felt comfortable testing the one leg.

The Good Governor checks voltage and line frequency.
Power Management The PowerPal came onto the market after we had the Good Governor.  This is a good testing tool.  It plugs into a 50 amps outlet so it can check both legs unlike the Good Governor without adapters.  The PowerPal also checks Ground and Neutral.  The PowerPal has a display plus it speaks the conditions observed.
Power Management During one of the sessions at Life On Wheels, taught by Steve Savage, we were convinced that our RV was at risk without a power management system.

The above tools check the park power post before connection.  A power management system continues to monitor park power while you are connected.

We chose the Progressive Industries PT50C version of its EMS (Electrical Management System) for these reasons:
  • Micro-processor driven with a led display to show current leg voltage, current and frequency, and any error condition.>

  • High voltage protection.  The EMS will disconnect park power from the RV if the line voltage goes over 132 volts.  High voltage can burn out electronic devices.

  • Low voltage protection.  The EMS will disconnect park power from the RV if the line voltage drops below 104 volts.  Low voltage can burn out motor devices like your air conditioner compressors.  Electrical devices really consume power (watts), the product of voltage (volts) and current (amps).  If the voltage goes down, then the current used will rise to maintain the same power.  This extra current draw is what burns out devices.

  • Surge protection. The EMS will protect your RV and devices from voltage spikes.  Spikes generally occur from lightening; but there are other sources of spikes.

  • Wiring error protection.  If the EMS senses that the park wiring is reversed, it will not turn on park power to your RV.

  • Open neutral protection.  If the EMS does not find Neutral continuity, it will not turn on park power to your RV.

  • Open Ground protection.  If the EMS does not find Ground continuity, it will not turn on park power to your RV.

  • AC frequency protection.  If the AC frequency drops below 51 Hz or goes over 69 Hz (60 Hz +/- 9Hz), the EMS will disconnect your RV from park power.  AC frequency errors can harm motors.

  • 220 volt protection.  The 50 amp plug on a RV power cord can be plugged into a 220 volts outlet.  The RV is wired for 110 volts.  If the EMS senses this error, it will not connect park power to your RV. Actually this is more likely to happen when using a 30-50 amp adapter and mistakenly plugging into a 220 volt 30 amp outlet.

The Progressive EMS is far more than just a surge protector.

We have already benefited from the Progressive EMS.  We were in a park with a poor neutral.  When we turned on a load like an air conditioner, that load on one leg of the park power would bring the voltage down a bit  This is normal.  However, with the poor neutral, the voltage drop on one leg showed up as a voltage increase on the other leg.  Because the Neutral was poor, the voltage drop on the load leg was more than normal and the other leg would climb over 132 volts.  Had we not had EMS protection, we would not have noticed the high voltage until something burned out.

Power Management The Progressive EMS is available in hard wired and portable styles.  The hard wired model is installed in you RV inline with the park power input.  The hard wired style can have its display built into the unit or as a remote display that can be mounted in a convenient location inside the RV.  There are 50 amp and 30 amp models.
Power Management The portable model plugs into the park power post and the RV power cord is plugged into the EMS.   There are 50 amp and 30 amp models.

We chose the portable unit mainly because finding a place to install a hard wired model in Tige would have been difficult.  This definitely an item to plan for if you are ordering a new RV.  The RV manufacturer can either install the EMS or at least leave space where it is easy to install a hard wired unit inline with the input power.

When the park power breaker is turned on (the breaker should always be off when plugging in the RV power cord), the EMS will sample the park power for a short time.  After several seconds, when the EMS has determined that the park power is safe, the EMS will connect park power to the RV.

If the EMS has to disconnect park power from the RV, the EMS will wait 136 seconds, then check park power to see if it is okay again, and if it is, reconnects park power to your RV.  This delay protects your air conditioners.  If power is reapplied to quickly to the compressor, pressure built up in the compressors can resist the compressor startup and damage the compressor.

If the EMS acts upon an error condition, it will retain that error condition in its display memory so that you can see if you are having electrical problems.  The display is built into the portable models.  For the hard wired models, the display is in a remote module that is mounted on an interior wall of your RV.

Power Management The Progressive EMS is not low cost and having it hang on a park power post makes it available to thieves.  The PT50C comes with a security bracket, a piece of steel the PT50C is mounted through with another hole for a locking device.  We use a cable locking device.  We pass the locking cable through the security bracket.

More importantly, we have found that using the locking cable, relieves the strain on the EMS plug in the power outlet.

We found the Master Lock Python 8413XDPF cable lock had an end that will fit through the security tab of the Progressive EMS.  The 6' length version of the Python gave us the ability to wrap the locking cable around the park power post and the PT50C EMS unit twice for extra security.

We still use our Good Governor.  Most of the AC devices we normally use are on the leg that is also driven by the inverter.  If the park power fails, the inverter immediately switches over and we do not even notice the switch.  We plug the Good Governor into an outlet that is not on the inverter leg.  If the display is not illuminated, we know that the park power is not on.

Disclaimer: The information in this site is a collection of data we derived from the vendors and from our personal experiences.  This information is meant as a learning guide for you to  make your own decisions  Best practices and code should always be followed.  The recommendations we make are from our personal experiences and we do not receive any compensation for those recommendations.
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