Can someone explain this please: (From ASME A17.1-2013)
2.26.1.5.1 When switching to either “BYPASS” or “OFF” position, they shall (a) have contacts that are positively opened mechanically; their opening shall not be solely dependent on springs, or (b) be SIL rated with a SIL equal to or greater than the SIL indicated for the applicable device shown in Table 2.26.4.3.2
The bypass switches are required by the code (2.26.1.5) and controller manufacturers have to include them. The code you referenced is simply describing the physical requirements of said switches so controller manufacturers have a standard they have to follow. We just turn them on or off..
The codes trying to maintain a level of safety in a critical circuit by requiring a certain type of switch. If they didn't there would most certainly be controller manufacturers going to very cheap unreliable components that could get someone killed.
I believe the key point here is 'POSITIVELY OPENED MECHANICALLY.' Positively opened switches ensure that the switch opens completely whenever the user toggles it. They don't rely on springs and are both simple and safe. Typically, a piece of metal is mechanically linked to the lever, and when the lever is moved, it compels the contact to open. They are usually slide type switches. In contrast, non-safety switches depend on springs. There's a possibility that the spring might malfunction, causing the contact to remain closed even after the user moves the lever. Therefore, it's of crucial importance that the type of switch used for 'INSPECTION/NORMAL' or 'HALL/CALL BYPASS' functions is of the positively opened kind.
Thank you, everyone, for the prompt replies. I raised this question because we have the maintenance of a 26 floor traction elevator. One of our technicians informed me that despite the controller being in inspection mode in the machine room, it was still operating at normal speed. I found this hard to believe until I personally inspected the controller. I discovered a faulty INSP/NORM switch on the main board. This sounded like a serious safety issue in the controller to me, and made me to delve into the code and ascertain that the type of switch being used for INSP/NORM is not in accordance with the specifications outlined in the code. I believed that sharing this information could also be beneficial for you as well and maybe help preventing injury and death.
Aw come on. These things are ridiculous, I'm adjusting one out right now..
Smartrise is really really not impressing me at all. They completely forgot to put the line reactor in the controller (it's on the prints). And the battery lowering device unit was defective, wouldn't charge the batteries. Called them for a warranty part. They sent me a new one. The new ones missing the fuse holder on the bottom of the board, I called and asked if I'd gotten a different version, guy says no its on there in the picture we took before shipping. It's in the bottom of the box. The entire fuse holder was never soldered, not broke off I mean the leads were brand new and contact pads were perfect, they put it on and never soldered it, then shipped it out and it fell off. Guy acts suprised and says they make those in house. Sends me a third unit, I asked that they actually test the third one before shipping. The third im pretty aint charging either but I'm not dealing with it until the rest of the cars adjusted out then I'll come back to it.
Did a C4 job one year ago, and never did another , told my boss I would not ride one these cars they are unsafe. Car moved on its own when on inspection , and when I told the support guy that, they acted like its no big deal. Big fan of MCE for tractions , as well I just did my first Alpha traction controller works great as well, and support is fantastic .
The reference to the SIL rating table is critical. SIL stands for safety integrity level and represents a reliability factor of a safety product. For example, SIL 1 means there is a 99.9% certainty that the product will function as needed. SIL 2 takes that to 99.99%. SIL 3 goes to 99.999%.
The table in section 2.26.4.3.2 says the inspection switch should be SIL 3. For the code to give an "either or option", that is mechanically activated or SIL rated does not make sense. It should be SIL rated period. Just because a manufacturer can claim a switch is "mechanically activated" does not mean that it has the same safety integrity as a SIL3 rated device.
