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Caledon Controls Ltd
Unit 2 Block 4
Castlehill Ind. Est., Carluke
Scotland ML8 5UF

Tel: +44 (0)1555 773355
Fax: +44 (0)1555 772212


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RLS Series for Resistive Loads

Thyristor stacks for resistive loads SRC series

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Integrated thyristor controllers for the control of 3-phase AC loads
Two versions - RLS2000 series for 2-leg control; RLS3000 series for 3-leg control
Wide 3-phase voltage range - 200V to 480V or 200V to 690V
Current ratings from 63A to 800A
Fitted with semiconductor fuses, snubber networks and MOVs where appropriate
Automatic phase rotation detection and line synchronisation
Comprehensive user selectable firing modes
Switch between two firing modes during operation using a digital input
Suitable for transformer coupled loads
Accept 0-5V, 0-10V, 1-5V, 2-10V, 0-20mA, 4-20mA control input
Also accept logic (SSR Drive) control signal in burst fire or single cycle burst fire mode
Auto / manual (local / remote) facility
Power limit facility
V2 control law available in phase angle mode (open loop)
Galvanically isolated digital inputs
Volt free alarm contacts for heatsink over-temperature and loss of a phase
Require a 24V DC supply for the control electronics and cooling fans


These controllers are designed for the control of 3-phase AC heating loads in either burst fire, single cycle burst fire or (3-leg control only) phase angle control modes. The comprehensive user-selectable range of firing modes ensures that the one most suitable for a particular application can be chosen - after trying the different modes if wished.

The controllers accept a standard analogue input control signal. A second analogue input may be used as a manual input (with external potentiometer) or as a power limit input, or the two inputs may be considered as a 'lowest wins' pair. The controllers may alternatively be configured to operate with a 'logic' control signal.

The load may be either 3-wire star or delta or (with 3-leg control only) 4-wire star connected. All types have modes suitable for the control of both resistive and transformer-coupled loads.

The controllers are suitable for use on 3-phase supplies with nominal line voltage between 200V and 480V RMS (phase voltage up to 277V) or between 200V and 690V (phase voltage up to 400V) depending on the voltage rating chosen (480V or 690V). Over this voltage range synchronisation and phase rotation is determined directly from the 3-phase supply via the 3-phase line connections. A separate synchronisation input is provided (using a special adapter) to enable operation on a 24V RMS supply for use on low voltage high current test rigs.

More detailed information is available on our downloads page, and comprehensive information on the available firing modes is in the data sheet for the RLS series thyristor drivers.


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