Note
The Network Rail RADAR system will not accept a digital start and end trigger from the same channel. You may only use a digital channel one time in any capture. For example, the set-up below:

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.

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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.

Info
Designers note, this solution almost doubles the cost of your point monitoring solution.

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.

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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.

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The RS485 link can become overloaded when used for point monitoring if all the monitored point ends move concurrently. Mpec recommend the following limitations:

Electrically driven machines (Motor current only) 8 concurrent switch ends

Hydraulically driven machines (Motor current and pressure) 4 concurrent switch ends

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title Sizing the System
Working out how many data loggers you require for a given installation is relatively simple. Count how many analogue and digital inputs are required Select the lowest cost data logger combination that satisfies these numbers of inputs: SA380TX Hardware Variants Configuration Analogue Inputs Digital Inputs Base Unit (No Cards) 0 10 Base Unit + 1 Digital Card 0 18 Base Unit + 2 Digital Cards 0 26 Base Unit + 1 Analogue Cards 4 10 Base Unit + 2 Analogue Cards 8 10 Base Unit + 1 Analogue Card + 1 Digital Card 4 18 The SA380TX is more expensive than the SA380TX-L, it does however have advanced features, such as the touchscreen, battery back-up, advanced data processing options and master/slave capability. SA380TX-L Hardware Variants Configuration Analogue Inputs Digital Inputs Base Unit (No Cards) 2 4 Base Unit + 1 Digital Card 2 12 Base Unit + 2 Digital Cards 2 20 Base Unit + 1 Analogue Cards 6 4 Base Unit + 2 Analogue Cards 10 4 Base Unit + 1 Analogue Card + 1 Digital Card 6 12 Master / Slave Devices As stand-alone devices, each data logger will require an active SIM and GSM antenna in order to transmit data to the RADAR system. This can become troublesome for large installations installed in tight spaces. Using a “Master / Slave” arrangement permits up to 7 SA380TX-L devices to connected over RS485. Image RemovedImage Removed All data is marshalled through the master SA380TX device. Consequently all configuration, data collection and transmission, is controlled from the master SA380TX. In theory the maximum number analogue channels become 78, and digital channels becomes 166.
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