Replacing a Crouzet PNR110A with a Macromatic SFP120A100 Seal Leak Relay

Seal Leakage & Over Temperature Relays


I have been using a Crouzet PNR110A liquid level relay as a seal leak relay. To make it work properly, I had to jumper pins 5 6. Now, I want to switch to the Macromatic SFP120A100 unit and notice no such jumper is shown on the connection diagram. Is it required or not?


Many submersible pump installations use a relay to monitor submersible pump seals for potential leakage. Products such as the PNR Series from Crouzet were designed as dual probe liquid level control relays but can also be used as seal leak relays (or pump seal failure relays).

When used as liquid level control relays, a Crouzet PNR110A typically requires a connection to a HIGH probe, LOW probe COMMON (See Diagram A).


Liquid pump with attached circuits

However, in seal leak monitoring applications, only two connections are required-a COM a PROBE. Therefore, to make a dual probe liquid level relay normally requiring three connections work as a seal leak relay needing only two connections, a jumper must be placed between the COMMON MAX probe terminals, which are usually pins 5 6 (see Diagram B).


Liquid pump with attached circuits

Recently, several manufacturers such as Macromatic have introduced dedicated pump seal failure relays. The SFP Series from Macromatic was designed to be used only as a seal leak monitor relay, never as a liquid level control relay. There are two versions available: a single channel unit for monitoring a single pump and a dual channel unit to monitor two pumps with isolated outputs (click here for additional product information).

A dedicated seal leak relay for a single channel application requires only two connections to the submersible pump-one to COM and one to the probe in the seal cavity of the submersible pump. However, these products were made to connect the PROBE to terminal 6, not terminal 8 (see Diagram C).


Liquid pump with attached circuits

Therefore, in order to make the SFP Series single channel seal leak relay work as a drop-in replacement for the Crouzet PNR110A that has a jumper wire between pins 5 6 per Diagram B, the following must be done (refer to Diagram D):

  • Remove the jumper wire between pins 5 6
  • Move the wire connected to pin 8 and reconnect it to pin 6


Liquid pump with attached circuits

Please note this discussion only pertains to installations where you are replacing a Crouzet PNR110A level control relay with a dedicated single channel seal leak relay. It does not apply to the Crouzet PNRU110A, which is a Pump Up level control relay and is not normally used in seal leak relay applications.

For installing a Macromatic seal leak relay in a new application, simply follow the installation instructions wiring diagram provided with the product. NOTE: If you want a true drop-in replacement for the PNR110A where no rewiring is required at all, Macromatic offers the LCP2G100. Like the PNR110A, the LCP2G100 is a dual probe pump down level control relay. It has the same pin configuration operation as the Crouzet PNR110A. It can easily replace any PNR110A without the need for rewiring in both seal leak level control applications.

Like the Crouzet PNR110A, the SSAC LLC54 Series is also a dual probe level control relay. However, its design prevents it from also being used as a seal leak relay as described above. Therefore, this Knowledge Base Article does not apply to the SSAC LLC54 Series.

For additional information or if you have any questions, please contact Macromatic Technical Support at 800-238-7474. You can also search our online Competitive Cross Reference for liquid level control & seal leak relays to find the equivalent Macromatic product.