If you take a modern earth leakage relay to bits, the delay is quite tightly defined either by a resistor capacitor time constant, or a micro-controllor counting clock cycles. Unless you have deep pockets it should  be a scrap one, as putting it back together is hard. There are DIP switches or twiddle knobs to set it.

Inside  an type S things are simpler,  the early ones just had a mechanical damping on the latch pull-off coil, and trip time varied with the degree of over-current, but the modern ones are closer to the analogue earth leakage relay, in using an RC delay, albeit one defined by the economics of the 20% tolerance parts bin, and some electronics and an SCR to fire a fairly sturdy actuator solenoid, these have a less variable  delay  once you get comfortably above the trip threshold.

As noted 

‘ Slower than the slowest instant trip model, and 
Fast enough to limit shock duration to less than a heartbeat’ 

was the original intention, though of course never written that way, and the spec is wide enough to accommodate all types.

Mike.

If you take a modern earth leakage relay to bits, the delay is quite tightly defined either by a resistor capacitor time constant, or a micro-controllor counting clock cycles. Unless you have deep pockets it should  be a scrap one, as putting it back together is hard. There are DIP switches or twiddle knobs to set it.

Inside  an type S things are simpler,  the early ones just had a mechanical damping on the latch pull-off coil, and trip time varied with the degree of over-current, but the modern ones are closer to the analogue earth leakage relay, in using an RC delay, albeit one defined by the economics of the 20% tolerance parts bin, and some electronics and an SCR to fire a fairly sturdy actuator solenoid, these have a less variable  delay  once you get comfortably above the trip threshold.

As noted 

‘ Slower than the slowest instant trip model, and 
Fast enough to limit shock duration to less than a heartbeat’ 

was the original intention, though of course never written that way, and the spec is wide enough to accommodate all types.

Mike.