Relay Logic

A relay is essentially an electrically controlled switch used to open or close an electric circuit. A control system using Relay Logic is referred to as an Electromechanical Control System. Relays are available in a wide range of styles; Plug in (tube type), Timing, Stepping, Alternating, Latch and Solid State.

Advantages over Programmable Controllers are; (1) You don't need a programming tool to work on the system. (2) You don't need someone who knows how to operate the programming tool.

Disadvantages are; (1) You can't make changes as easily. (2) With a big system, it will probably cost more.

When Exman Electric designs an Electromechanical Control System it is kept as simple as possible with no extra parts!

Below is a picture of an Electromechanical Control System.

• (A/B) Dual Pumping System
• System A 3- 1/4 HP DC Drives
• System B 2- 1/4 HP DC Drives
• Dual Resin Slow/Fast (From remote switch)
• Full Auto and Hand Operation
• Size 1 Motor starter
• Calibration Timer
• Auto Purge timer
• Power On Push Button
• Emergency Stop Button
• 30 Amp Fusible Disconnect
• 480/240 Volt, 3 Phase Input Power
• NEMA 12- 36X26X8 Enclosure

Inside This Control System

• Five 1/4 HP DC Drives.
• 1000VA Transformer.
• 30 Amp Fusible Disconnect
• Two Solid State Timers
• Four AB Relays
• One Size 1 Motor Starter
• Primary Fuse Block
• Secondary Fuse Clip
• Terminal Blocks
• Ground Bar
• Perma Sleeve Wire Markers
• 480/240 Volt, 3 Phase Input Power
• Nema 12- 36X26X8 Enclosure
• White Wire Duct
• MCR Master Control Relay

The Door Layout

• Digital Eagle Timer
• Allen Bradley Switches
• Wire Duct
• Push Button Rheostats
• Spiral Wrap
• Perma Sleeve Wire Markers
• Heater Element Selection Table