Adding a gate to light curtain circuit

Hi, we have a punch press machine with a light curtain with 1M-T-9A Banner safety relay.

We are adding a simple limit switch for a gate(guard). As you can see in the picture, I am adding a relay that is energized when the gate is closed. The light curtain signal wires go through the relay contacts.

Is this safe? Any better ideas? Thank you.

What are you trying to achieve with this?

In regards to safety you won't be able to get a solid answer because it falls back onto doing a risk assessment and being able asses the equipment in a way that's not possible on an internet forum.

With that being said the existing circuit (light curtain and safety relay) is a 2 channel safety circuit and to remain at the existing safety level you would at least need a 2 channel safety switch. A single pole gate feeding a relay would not satisfy that condition.

Most likely (again depends on risk assessment) you would need to utilize an additional safety controller. Besides the single switch issue also what you are showing creates a fault mask. In general a two channel safety relay checks that both signals coming in are on and that they turn on at the same time (within a few milliseconds). In your circuit if there was an issue with either the gate or the light curtain (as far as turning off/on at the same time) you could simply open the other circuit to reset the controller which isn't good practice nor acceptable for PLd or PLe applications.

I'm sure if you can provide more detail on the application someone can nudge you in the right direction.

In addition to what titanspark76 has posted, it is also important to remember that there is a de-rating for series connected SRPCS'. What are you using for a gate switch?

As was already mentioned, a risk assessment is necessary to do this properly. But here are my observations based on the information you provided:
1. The gate switch needs to be safety rated with redundant contacts or signals.
2. When adding relays to a safety circuit, you always have to consider the possibility that the relay contacts could stick closed. Your relay CR would need to be force-guided type with monitoring contacts connected to a proper safety relay. (The IM-T-9A is not a true safety relay in this sense as it can't monitor other devices--Banner calls it an "interface relay.") Fault masking is also a concern as was mentioned already.
3. You mentioned this is for a punch press. OSHA has very specific safety requirements for presses so I'd think twice before you start tinkering--see 1910.217.

Is this gate going to allow someone to be beyond the light curtains?