10ATR

EWNR

10 BTR

10ATR

10 BTR

1ASR

2ASR

4ASR

17/19OVSR

10WLR

EWNR

10 NLR (R)

10WLR

10WNR

WNNR

10RLR

10 NLR

10 RLR (R)

W RNR

10 NLR

10 RLR

10NLR

10WJR

10XR

10XR

10RLR

10 XR

10NKR

10RKR

10 WJR

10WLR

10 WJR

10 WJR

10 WJR

10 WJR

10 XR

10 WJR

10RLR

10 NLR

10NKR

10NWC

10NLR

10RLR

10RKR

10RWC

10NWC

NM

10NWC

10RWC

10RWC

RM

20NWC

20RWC

EWN

EWNR

10NWC

(ADD ALL POINT CONTACTOR BACK CONTACTS)

P

CM

10NKR

10RLR

10NLR

N Detect

10RWC

10RKR

10NLR

10RLR

R Detect

The NLR and RLR relays shown are magnetically latched relays. Coils marked (R) are the release coils

RWC and NWC are  POINT CONTACTORS

Working of the circuit

The operating panel assumed in this circuit is  push button type. Operation of the point will require the operator to operate the point control button provided for that point (10WN) and any one of the common point call buttons (WNN or WRN) depending on whether the point is to be called to normal or to reverse. If the point track circuit is occupied the operation will require a common emergency operation button (EWN) to be operated along with the two buttons required for normal operation.

WLR proves point is free to be operated. 10ATR and 10BTR is the direct locking of the point by the point track circuit. If the point track circuit is occupied WLR will drop and ensure the point cannot be moved. The ASR contacts prove that no route has been set over the point. The OVSR contact prove that the point is not in the overlap of any route which has been set.

The WNNR (WRNR) and 10WNR are the contacts of the button relays which pick up when the point is attempted to be called to the normal (reverse) lie from the control panel..

WLR is picked up unless it is in the route or in the overlap of a called route. The point is called  by operating the common point control buttons which pick up WNNR for call to normal position or WRNR for call to reverse position and the point selection button for 10 which pick up 10WNR. 

When 10WNR is picked up along with WNNR it causes 10RLR to be released and then 10NLR is picked up and latched. When 10WNR is piocked up along with WRNR it will cause 10NLR to be released and then 10RLR will pick and latch.

When 10NLR or 10RLR is picked up with the detection in the field in the opposite direction it causes both the point detection contacts 10NLR and 10RLR to drop. This picks up 10WJR. When 10WJR is pick up it picks up 10XR. When 10XR is picked up the feed to 10WJR is disconnected. 10WJR  is made slow to release due to the resistance capacitor combination across the relay coil and so 10WJR does not drop till about 20 seconds.

When 10XR picks up it causes 10NWC to pick up for call to normal position or 10RWC for a call to reverse position. when 10NWC or 10RWC is picked up its feed is extended to the point machine and the point machine moves. If the point machine operates and the point moves to the called position within 20 seconds (before 10WJR drops) the 10NKR or 10RKR relay picks up depends on whether the point was called to the normal or the reverse position.

When the detection in the called position is achieved 10WJR drops. 10XR remains picked up till the call is removed by releasing the point calling buttons.

If detection is not achieved then 10WJR drops away after 20 seconds and cannot be re-picked unless the point operating buttons are re-operated after releasing them.

Facility is provided to operate the point if the point track is occupied by operating emeregency point operating button along with the point control buttons. When the emergency button is operated it bypasses the track circuit contacts in the WLR circuit and allows 10WLR to pick. Once 10WLR picks the point can be operated in the same way as for normal operation.