Elevator Pre-Signal Feature
Elevator Pre-Signal Feature
Does anyone know what kind of connection (type, size, and quantity of wire) is typically required between an ATS and an elevator controller. This connection is to notify the controller that power is going to be transferred from normal to emergency and allows time for the cabs to drop to the main floor prior to power being "restored."
I can't seem to find any details on the actual connection anywhere!
Thanks,
Keri
All of these replies are giving you the correct info but allow me to elaborate on the subject.
Basically, an elevator pre-signal, pre-transfer feature signals the elevator controller prior to a hot-bus hot-bus transfer (both sources energized.) This normally occurs when the ATS transfers back from gen to utility during a power outage or as stated, when the test button is used for initiating the transfer. During a power outage the feature is not activated on transfer to gen since this is a dead-bus hot-bus transfer (no utility power on ATS.) This feature, although can be found on the older relay logic ATSs, was not normally required with the controllers that used relay logic. However, it is extremely critical with the newer solid state controller logic on new installs or when old equipment is upgraded. The point is that the car cannot be moving during the switching of the motor load from one hot source to another with solid state controllers. Equipment damage such as blown circuit boards and components in the elevator controller can and will occur.
Part of my business involves designing and installing this feature on older systems (25 to 35 yrs) that have been upgraded.
Normally what I find is that the elevator vendor requires 2 seperate dry contacts that either NO or NC depending on the particular design/ Manuf. One contact operates 20 sec (adjustable) prior to transfer of the ATS. This signal sends the car to the nearest floor and the doors open. After transfer occurs, the contact resets and the car continues as normal. The second set of dry contacts operates after the ATS is in the emer position. Usually this signal puts the controller in emer mode and only allows for 1 car to operate on gen since they are not designed to power the whole bank of cars. We call
this the Switch Position contact. When norm power is restored, the sequence repeats in the retransfer to utility and both
contacts reset for normal elevator operation.
So depending on how the spec is written I usually see (4) #12 or #14 gauge (THHN, 600V building wire) field wires pulled between ATS and elevator room. I always recommend pulling spare wires for future use: wire is cheap compared to labor
PS: forgot to mention, on the older ATSs these field wires connect to a TB block and use plugin timers/relays. On the newer ATSs with microprocessors the connections are at the back of the processor and time delay is programmed in from the HMI touch pad.
