Three-Phase Monitor Relays
Does my Phase Monitor Relay require a Short Circuit Rating?
Issue: I have an application where the panel control voltage is at 120V AC, but I need to have a 24V DC alarm circuit if the three-phase monitor relay trips. How can I do it without adding a relay to the circuit?
Issue: Are fuses required and what size fuse do you recommend using with your Phase Monitor Relays? Solution/Resolution: The use of fusing in-line with Macromatic phase monitor relays is not required; however, Macromatic recommends using a 2 ampere, fast acting, voltage appropriate fuses such as a KTK fuse between the Phase Monitor Relay and the three phases (see diagram below). Use of fusing in-line with loads controlled by the relay output should also be considered depending on the application. Marked safety and regulatory approvals, including UL Certifications, do not require the use of inline fuses in typical applications. Please be aware that different guidelines may apply in your specific application and/or installation.
Issue: Can Macromatic's 3 phase monitor relays be used with open delta systems?
Answer: Yes, by following a few simple guidelines.
Modification to Order a Product that is Normally an 8 Pin Product with 11 Pins (-H Suffix) No Longer AvailableTuesday: December 1, 2015
Issue: In the past I have purchased a time delay relay with the H option, but it is now obsolete. What can I do? Solution/Resolution: We certainly apologize that this option is no longer available and therefore, may cause some inconvenience for you. This option was to take a time delay relay that normally came
Issue: Can I use a phase monitor for protection on a high-leg delta system? Answer: Yes, Macromatic phase monitor relays provide the same reliable protection on high-leg delta systems. A high-leg delta system (also commonly called red leg and wild leg among others) is a common configuration involving a transformer secondary having one winding center tapped
Issue: I have never connected a three-phase monitor relay. Do you have a typical wiring connection? Solution/Resolution: While each individual application may have its own requirements, this diagram showing a three-phase monitor relay and motor starter is fairly typical of most installations. When the three-phase voltage is present and all conditions are normal, the N.O.
Issue: Schneider Electric (Square D) has obsoleted their complete line of 8430 MPS plug-in & MPD surface-mount phase monitor relays. I see Macromatic has several products I could use to replace the Square D products. Are there any special issues to address? Solution/Resolution: The following are the steps required to replace an obsolete Square D product with one from Macromatic
In May 2015, Macromatic introduced the next generation of PMD Series Three-Phase Monitor Relays. Many important features were added to the new products. These improvements along with a comparison to the previous design are summarized.