Macromatic Product and Technical Articles

When designing Intrinsically Safe Circuits, it is imperative to understand the entity parameters of the devices in your circuit. The entity parameters describe characteristics of the device, as well as what can safely be connected to it. 

Since the 2005 edition, the NFPA70: National Electrical Code (NEC) requires that industrial control panels must be marked with an appropriate short circuit current rating (SCCR).  The SCCR value in kA, at a defined voltage, is an indication of what fault current the industrial control panel can withstand (without unacceptable damage) in the event of a fault.  

Intrinsically Safe devices are not yet required to meet UL 913 8th Edition. So why does certification to the more stringent 8th Edition matter?

We are often asked several questions regarding our plug-in products & UL certifications: Why are some products only UL Component Recognized instead of UL Listed”? and What is the difference between UL Component Recognized & UL Listed”? 

Depending on the function selected, not every time delay is possible with this unit.  For example, time delays of 12.55 Seconds or 145.5 Minutes are not valid settings for Single Mode functions. 

This simple solution can be done with one Interval ON (TD1) & two Single Shot (TD2 & TD3) time delay relays.

Schneider Electric (Square D) has obsoleted their complete line of 8430 MPS plug-in & MPD surface-mount phase monitor relays.

Issue: On any of your current sensing relays, is there a maximum voltage level for the current being monitored? 

Alternating Relays with DPDT cross-wired output configurations are typically used to control two loads when the need to have both loads on at the same time for additional capacity is required.

Issue: The output relay appears to be already energized on my True Off Delay timer without any input voltage applied.  It was that way when I received it or I found it in that state during installation.  What happened and how do I fix it?

Many submersible pump installations use a relay to monitor submersible pump seals for potential leakage.

Issue: Can I use an Alternating Relay with one input voltage value to control multiple loads at a different voltage?