Gate Safety Edges

[Onoff]

I need to fit a couple of wireless safety edges. Though the concept isn't new to me, actually specifying, buying and fitting them is.

A quick learn tells me there are mechanical contact strips and resistive types. Furthermore you get "end" ones with 1 cable and "through" ones with 2 cables.

On the gate control PCB, across 20-21, is an 8k2 resistor.

The secondhand, "working when removed" transmitters and receivers I've just bought look like this:

Am I right that I can use mechanical (NC) rather than resistive contact strips and just select which via the DIP switches on the transmitter TX? It appears you could have an NC input on IN 1 and a resistive 8k2 input on IN 2 or vice versa.

Are resistive strips better / safer than mechanical ones?

The receiver RX appears to offer either an NC or 8k2 output. As my gate PCB appears to be expecting an 8k2 input I presume the jumper must be set to that. Furthermore I presume the receiver, set to 8k2 takes the place of the resistor?

I wonder then if I could use mechanical strips to feed the transmitter but have the revceiver set to 8k2?

Just need to find a couple of 1.8m black, contact strips now.

Any pointers / insght on this appreciated!

Cheers.

 

[JOEPRO]

As an aside, in terms of safety when I was making and automating my own house double gates I researched this and another method is to have the motors monitor and provide this function.

So I went for more expensive motors which included encoders. The pressure and sensitivity of the gates is adjustable and monitored at all times. Very reliable system and simple really as no extra kit to lose connections and have future issues.

I have mine set such that they would not hurt a small animal if caught between the leaves when opening or closing. And I test this by grabbing a gate leaf myself in operation every couple of months and all good some 5 odd years later.

I think this is a better method but if this is a retrofit and you must therefore use pressure sensitive edges that is a different story.

Important reading on the pressure sensitive gate standards here - temperature limitations and 3 month testing requirements!

Pressure Edges - the standard in plain English - Gate Safe

31 pages of the standard are devoted to how to test pressure edges. In reality, how many automated gate installation companies would a) be able to afford to purchase the standard b) have the time to read it c) understand the terminology and the intricacies of the tests involved?

blog.gate-safe.org

• Firstly, and most importantly the pressure edges should be configured so that they fail safe preventing the machine from operating until the obstruction is cleared.

• The size of the profile selected should take into consideration the need for the gate to operate effectively based on its average travel speed

• As part of the manufacturing process the edge should be tested in excess of 10000 operations. After each operation, the deformation of the edge must return to more than 80% of its original size in 30 seconds and 95% after 30 minutes

• The standard requires that pressure edges must be capable of operating at temperatures as low as minus 5 degrees. Given temperatures in the north of the country during the winter months, this gives cause for concern as to the degree of safety afforded by pressure edges during periods of extreme cold weather!

• The controller for the edge must be fitted into a weather proof housing IP 67 if it is sited in a position where there is the potential for it to become immersed in water

 

[Onoff]

Erm...so back to my original question!

Gates, motor etc all in. Was just after someone with experience of these contact strips.

 

[Robotstar5]

Resistive strips are a bit misleading, I think they mean a "mechanical" contact strip with an 8k2 resistor across the end (connects the 2 contact strips), it is inherently safer than the non-resistor type as the control unit can constantly monitor the safe edge for damage, broken supply wire etc. and put the system into fault if a break is detected, the 8k2 type also stops anyone trying to link out the monitored contacts unless they put an 8k2 resistor across it (I always carried a couple of resistors in my tool bag )
An un-monitored/non 8k2 strip would not be allowed in an industrial safety system.
Your RX unit should be connected to a 2 channel monitored safety relay to make it fail safe.

 

[Onoff]

Is there a requirement for a gate safety edge to go all the way to the floor (this on a sliding gate)?

Total height is 1.8m. I was thinking fit a 1.7m and have it 100mm above the paved driveway.

 

[Robotstar5]

I don't know about gates, but machine guards, light curtains etc. should be no more than 180mm from the floor.

 

[sako243]

So I went for more expensive motors which included encoders. The pressure and sensitivity of the gates is adjustable and monitored at all times. Very reliable system and simple really as no extra kit to lose connections and have future issues.

I have mine set such that they would not hurt a small animal if caught between the leaves when opening or closing. And I test this by grabbing a gate leaf myself in operation every couple of months and all good some 5 odd years later.

I think this is a better method but if this is a retrofit and you must therefore use pressure sensitive edges that is a different story.

Only works if the pressure needed to overcome wind resistance is less than that required to crush someone. For example @8ob has a set of gates that pretty much max out the hydraulic rams when the wind is blowing down the drive. A friend of his has a large set of gates that were snapping the rods on the largest FAAC rams due to wind forces.

In those instances I can't see a way around having some auxiliary sensors such as the pressure strips.

 

[Onoff]

Safety edges turned up. The idiot that I am ordered x2 1.2m long ones instead of x2 2m ones!

 

[Onoff]

Useless companies and useless couriers!

Both 2m contact strips are damaged and at the end that the instructions say shouldn't be trimmed.

https://flic.kr/p/2qn8JWH

https://flic.kr/p/2qnfywJ

 

[Onoff]

I can only get one safety edge to work.

I've a transmitter that'll take ostensibly 2 safety edges. I've wired a safety edge to 9&8 and the other to 8&7 as in 8 is the common.

My gate PCB though only has a two wire input on 20 & 21. So I've 3&4 from the RX PCB going to 20&21 below:

Any ideas? Cheers.

 

[Blobber]

I would assume that the RX board is 2 channel, 3&4 being 1 channel and 5&6 being the 2nd channel corresponding with the 2 channels of the safety edge transmitter board, I guess you would need to find a way of combining both outputs 3&4 and 5&6
Can the safety edges be wired in series so you only use one channel on the TX board?

 

[Onoff]

I would assume that the RX board is 2 channel, 3&4 being 1 channel and 5&6 being the 2nd channel corresponding with the 2 channels of the safety edge transmitter board, I guess you would need to find a way of combining both outputs 3&4 and 5&6
Can the safety edges be wired in series so you only use one channel on the TX board?

Yes the RX board is 2 channel, on OUT N/R 1 and OUT N/R 2. Corresponds with the two TX inputs, IN 1 & IN 2.

The gate board is one make, the TX & RX another and the contact strips another. The only thing they have in common is that they're all Italian!

These are the wiring configurations that came with the contact strips but shown connected to a gate board different to the one I have.

I'll keep trying different configurations.

 

[Blobber]

It looks like you can just wire the 2 safety edges in parallel on one channel then?

 

[Onoff]

It looks like you can just wire the 2 safety edges in parallel on one channel then?

I'm going to go back and check but pretty sure I've wired the two gate strips as per 7B, so in parallel then into IN 1 of the transmitter.

I'm wondering if my particular transmitter input needs to see 8k2 only or zero ohms in the event of the contact strip being made. With two strips in parallel I'm assuming it's seeing 4k1. If one contact strip is made the transmitter then sees 8k2 from the remaining contact strip that's not been made.

 

[sparkysy]

If you have wired them in parallel then both will need to be activated together for it to work.
If they are series connected then either will isolate the gate.

 

[Onoff]

If you have wired them in parallel then both will need to be activated together for it to work.
If they are series connected then either will isolate the gate.

The transmitter, via DIP switches 2 &3 can be configured to accept either a NC safety edge or a resistive safety edge at 8k2. Doesn't putting two in series present the transmitter with 16k4 then zero ohms if either safety edge is made?

Sure I've tried in series but I'll revisit

 

[knighty]

Only works if the pressure needed to overcome wind resistance is less than that required to crush someone. For example @8ob has a set of gates that pretty much max out the hydraulic rams when the wind is blowing down the drive. A friend of his has a large set of gates that were snapping the rods on the largest FAAC rams due to wind forces.

In those instances I can't see a way around having some auxiliary sensors such as the pressure strips.

@8ob (or anyone else) any pics or description of setup?

I'm a bit worried the electric actuators for my gate are a bit small, I'm tempted to double them up

(tho gates a LOT smaller than yours I suspect)