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Typical Arrangement and Sensor Selection
Expand
titleSite Identification
title

Every data logger that is to be connected to the Network Rail RADAR system must:

  • Follow a defined naming convention

  • Have a unique device ID

Logger Name

The naming convention is of the form Engineers Line Reference (ELR):

  • Local Location Code specified by the local delivery unit, followed by an underscore, followed by

the route name

  • a

  • Engineers Line Reference (ELR), followed by an underscore, followed by a

2 digit number

The

  • 2 digit number

is

  • used to identify an individual data logger if more than one data logger shares the same

ELR.

  • location.

Info

Contact the Network Rail Delivery Unit to obtain a list of preferred logger names

Device ID

Every Mpec data logger connected to the Network Rail RADAR system must be assigned a unique device ID by the Network Rail RADAR team. The number will be between 1 and 65,534. No other RADAR logger must share this number.

Note

If numbers are shared, the RADAR system is unable to map the incoming asset data to the correct asset in the RADAR server system.

Expand

number.

Info

Each Network Rail delivery unit manages a “pool” of device IDs. Contact the Network Rail Delivery Unit to obtain a list of device IDs

Note

If numbers are shared, the RADAR system is unable to map the incoming asset data to the correct asset in the RADAR server system.

Expand
titleTypical Arrangement and Sensor Selection

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

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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.

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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.

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

N-R

R-N

Start Trigger

700 RWR DN to UP

700 NWR DN to UP

End Trigger

700 WI < 0.5 A

700 WI < 0.5 A

Capture Channel

700 WI

700 WI

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:

This will not work - Same Digital Channel used for start and end trigger!

Start Trigger

700 RWR DN to UP

End Trigger

700 RWR UP to DN

Capture Channel

700 WI

Use of detection relays

N-R

R-N

Start Trigger

700 NWKR UP to DN

700 RWKR UP to DN

End Trigger

700 RWKR DN to UP

700 NWKR DN to UP

Capture Channel

700 WI

700 WI

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.

Image Added

N-R

R-N

Start Trigger

700 WI > +5 A

700 WI < -5 A

End Trigger

700 WI < +0.5 A

700 WI > -0.5 A

Capture Channel

700 WI

700 WI

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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N-R

R-N

Start Trigger

700 RWI > +5 A

700 NWI > +5 A

End Trigger

700 RWI < +0.5 A

700 NWI < +0.5 A

Capture Channel

700 RWI

700 NWI

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.

Image Added

N-R

R-N

Start Trigger

700 RWP > +5 BAR

700 NWP > +5 BAR

End Trigger

700 RWP < +5 BAR

700 NWP < +5 BAR

Capture Channel

700 WI, 700 RWP

700 WI, 700 NWP

Expand
titleSizing the System

Working out how many data loggers you require for a given installation is relatively simple.

  1. Count how many analogue and digital inputs are required

  2. 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.

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.

Note

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

Info

100 Ohm Resistors on RS485 lines are there to supress reflections.

  • These are required at each end of the link if the total link length exceeds 300m.

  • Fitment on shorter cable runs reduces signal to noise ratio, increasing the chance of data corruption in the presence of noise.

The specification for the resistors is 100 to 120 Ohms. 5% tolerance or better, 1/4 Watt or better.

Info

Master / Slave networking requires a modern SA380TX variant of Modstate 3 onward

Determine the Mod State of an SA380TX

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titlePower & Earthing Arrangements

SA380TX

The power supply is internally isolated from earth and the rest of the SA380TX.

Power can therefore be taken directly from the signalling 110V supply and no additional isolating transformer is required.

The earth pin of the IEC C6 socket is not connected internally.  The unit must be earthed through its connection to the equipment racking.

The unit requires earthing for functional purposes (EMC ground). The unit does not require a protective earth connection in a rail environment.

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SA380TX-L

The power supply is internally isolated from earth and the rest of the SA380TX-L

Power can therefore be taken directly from the signalling 110V supply and no additional isolating transformer is required.

The earth pin of the mini-fit socket is connected internally.  The unit may be earthed through its connection to the equipment racking or through the power cable.

The unit requires earthing for functional purposes (EMC ground). The unit does not require a protective earth connection in a rail environment.

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