How to ON & OFF Relay Type Feedback in Delta VFD

Hi and welcome to this lesson. In this lesson/article, we are going to learn how we can how to switch on and switch off a relay type feedback system in delta vfd. Feedback is like, which we want to read some, some various information from the drive in our plc (programmable logic controllers), or hmi (human machine interface), or the indicators.

Feedback is generally, suppose i want to know that drive is running or not, so, you can have a feedback of vfd operation. If the vfd is running, i can have a feedback on led or in the plc or hmi. Which says, the drive is running. For example we have an external fault in the delta vfd, so in case of fault, as vfd shows us a status of "er" which means external error in the delta vfd.


Now, when the vfd is stopped. We want to have a feedback, or alarm, or indicator or in the plc or hmi. And you can see how we can have a desired frequency attained feedback from the drive. Let's start learning one by one.

Delta VFD Relay Feedback ON/OFF

In the bottom side of the drive, there are three feedback terminals you can see. Actually there is a relay inside the drive which is a feedback relay. So, what we are doing with this terminal is, we know that in the relay, we have one normally open and normally close (no and nc terminals), so the "rc" is common, "rb" is normally close and "ra" is normally open contacts of the feedback relay. As we know that, common is connected to normally close contact in normal condition, when relay energize, common contact connects to normally open contact. Alright.


What i have done is, i have connected 24 volts directly to the common, and the "rb" which is normally close contact is going to input 6 of my plc as shown in the diagram above. The normally open contact is going to input 5. Now, when the vfd is running, you will find, plc input will get on. To do that, we have parameter number 46 which says multi function output terminal 2 (relay output). This parameter is 07 by default which means fault indication. So in parameter 46, put "00" there which is "ac drive operation".


Now, when you will run the drive, you will see the signal of "6" is on which is coming from the drive. This says vfd is running. This is the feedback from the drive. Later we can use this feedback in HMI to show the text when the drive is running. So this is the very basic feedback system from the drive.