Digital Event Monitoring

Straight forward. Select the volt-free-contacts you wish to monitor and connect them.

• Check that polarity across the contact is correct.

• You may use Front or Back contacts

• You can be creative, using logic if you are short of inputs

DC Track Circuit Monitoring

Consumes 1 x Analogue Channel per track circuit.

Straight forward. Connect 1 x Rowe Hankins 600 mA CT such that it captures the current flowing through the track relay coil.

Point Machine Monitoring

One Motor CT - Relay Triggers

This solution consumes 1 x Analogue Channel and 2 x Digital Channels (max) per point end.

Current carrying conductors that carry full motor current in both directions of movement to pass through a PCM20 CT in the same direction. CT produces a positive direction waveform under all scenarios

• Command / Calling Relays

• Motor Relays

• Detection Relays

• Where no VFCs exist - Use “trip” output current clamps.

When monitoring multiple ends of the same point identity, VFC trigger inputs can often be shared amongst triggered captures, economising on inputs.

Using time-of-operation Relays (Calling or motor relays that are only active when the motor runs)

Using calling relays that remain picked after operation ceases (standard NR relay circuits)

Use of detection relays

Once Motor CT - No Relay Triggers

This solution consumes 1 x Analogue Channels per point end.

Where the Normal to Reverse and Reverse to Normal motor feeds can be detected in isolation you can use a single PCM30 CT to act as motor current capture and trigger.

Current carrying conductors that carry current during normal to reverse operation are fed through the CT in one direction, whilst conductors carrying current during reverse to normal operation are fed through the CT in the opposing direction. This produces a positive waveform from the CT during normal to reverse operation, and a negative waveform from the CT during reverse to normal operation.

Triggers can be taken from the analogue data. No VFC inputs are required.

Two Motor CTs - No Relays Triggers

This solution consumes 2 x Analogue Channel per point end.

If LEM PCM30 sensors cannot be sourced, or it is not practical to route all motor current conductors through a single CT, then as a last resort, two LEM PCM20 sensors can be used to monitor a single set of points.

Current carrying conductors that carry current during normal to reverse operation are fed through one of the CTs, whilst conductors carrying current during reverse to normal operation are fed through the other CT. This produces a positive waveform on both CTs, however, only one CT will be active at any one time.

Triggers can be taken from the analogue data. No VFC inputs are required.

One Motor CT - Two Hydraulic Pressure CT

This solution consumes 3 x Analogue Channel per point end.

The cost of this solution is offset by the fact that the hydraulic sensors are incorporated into the switch machine power pack and do not incur additional expense.

In clamp-lock machines, the motor always turns in the same direction. Current carrying conductors that carry full motor current pass through a PCM20 CT in the same direction. The CT produces a positive direction waveform under all scenarios.

Two pressure transducers are connected. One transducer will only register pressure when operating in the normal to reverse direction. The other transducer will only register pressure when operating in the reverse to normal direction.

The pressure transducers can be used to act as event triggers.