IDA4 Application Note

A hand operated crane with electro magnet for moving scrap metal.

In this application a hand operated crane at a steel plant, controlled by a PLC is being used to move steel bars with a magnetic lifting system. The client needed to monitor the DC currents drawn by the electromagnet which are between 0.5 to 15 Amperes DC. They required:

• A low alarm to detect the magnet current dropping to less than 0.5 ampere
• A high alarm to detect the magnet current exceeding 15 Amperes
• A ‘window’ alarm that would be active between a minimum and maximum level..

We offered our IDA4 set point controller for this application because:

• It has touch switch programming of the numbers on the 4.5 display
• Each output can be programmed as a high alarm, low alarm or window alarm.
• The alarm setting procedure is easy to understand and operate. To avoid relay chatter, you don’t have to understand dead band. For example, the instrument is scaled as 0-15.00 amperes, output one is set as a high alarm and is programmed to go into alarm condition at 14.9 amperes and come out of alarm condition at 14.3 amperes. You just need to program a turn on and turn off point.  

The control alarm or ‘window alarm’ uses a maximum and a minimum value. This function is useful if you want an monitor that a signal is between set levels. In this application because the crane was hand operated the client wanted to have visible indication. A red light if the current was above 14.9 amps, an orange light if the current was below 0.5 amps and a green light if the current was between 1.00 to 14.0 amperes.

Related Products

IDA4: Four Setpoint Alarm Controller

More like this