Thyristor Modules

SRC 2000-125A Thyristor Stack

STA101-125A Thyristor Stack

SRC1000-800A Thyristor stack

SRC2000-315A Thyristor stack

STA203-125A Thyristor stack

AMOT 130 Auto/manual station

Modbus Current and Voltage Monitor

Thyristor Stacks for Industrial Heating Applications

What Are Thyristors?

The thyristor, or silicon controlled rectifier (SCR) is a semiconductor device which can be used to switch electric currents. The thyristor was invented in 1957, and today devices are available which are suitable for switching currents ranging from a few milliamps at tens of volts to thousands of amps at thousands of volts.

Thyristors are very robust devices in semiconductor terms - more so than transistors or IGBTs and are well suited to service in industrial environments. Each device conducts current in one direction only, and to control an AC load two devices are connected back to back.

The thyristor stacks we supply are assemblies of devices wired for the control of AC loads, together with all the necessary control electronics and protection devices, enclosed in a unit suitable for mounting in a control cabinet.

Why Use Thyristors?

Thyristors are the preferred method of power control in heating applications, offering silent, long life control. Although it is possible to use electromechanical contactors in many applications, the switching frequency required to obtain good temperature control means that in higher power applications, contact life is rarely longer than a year. By contrast thyristors have no short term wearout mechanism, and will operate reliably for the lifetime of most plant. The products described in this brochure are generally much more robust than solid state relays, offering much better surge withstand capability, and operation at higher ambient temperature. They are also fully engineered with built in snubbers, MOV spike protection, semiconductor fuses, EMC filters and protective covers.

The Caledon Range

Caledon thyristor stacks are suitable for use in most electroheat installations, in particular in furnaces, ovens, dryers and general medium and high power heating applications. A comprehensive range of input control signals is catered for, including logic, 4-20mA, 0-5V, 1-5V, 0-10V.

Burst Fire Models

Burst fire operation enables compliance with the European EMC directive without the use of complex filters, and operation without degradation of the load power factor.

There is a range for the control of resistive loads (SRC Series) and also for control of transformer coupled loads (STA Series). The latter are designed to eliminate transformer in rush currents, and have been used successfully to control transformer coupled loads up to 360kVA. These models are not suitable for applications requiring current limit control, which require phase angle operation. We have detailed application notes on request, and our engineers will be pleased to advise on specific applications.

The SR range has now been superseded by the SRC range, but spare parts are still available, and some models can also be supplied to order.

Phase angle / Soft start burst fire Models

The STC3000 Series offers phase angle or soft start burst fire control of 3-phase loads. This range has comprehensive load feedback options and current limit, making it suitable for the control of complex loads. Modbus compatible communications facilities are fitted as standard and DeviceNet or Profibus DP fieldbus connectivity is available as an option

	63A to 1000A, 1, 2 or 3 -phase, rated at 50oC ambient.
	Ranges for resistive loads and transformer coupled loads.
	SRC and STA ranges can meet European EMC requirements without inductive filters

Data Sheets

Extracts from data sheets are available to view in HTML format, with larger pictures, or the entire datasheet is available to view or download in acrobat format (.pdf)
Note the SR series are not for new applications - use SRC series

Application Notes - .pdf format

Introduction to Thyristor Stacks from Caledon
Using Thyristors in Heating Control Applications
European Low Voltage and EMC Directives and their application to systems incorporating Caledon thyristor stacks

Manuals - .pdf format
Note the SR series are not for new applications - use SRC series

SR Series thyristor stacks for resistive loads, 80 - 200A
SR Series thyristor stacks for resistive loads, 315A and above
SRC 2000 Series thyristor stacks for resistive loads, 63-200A
SRC Series thyristor stacks for resistive loads, 315-800A
STA Series thyristor stacks for transformer coupled loads, 80A - 600A STC Series thyristor stacks for complex loads

Dimensional Drawings - SR and STA stacks .pdf format
(Dimensions of SRC and STC stacks are included in the manuals)
Note the SR series are not for new applications - use SRC series

SR 80A Stack (without semiconductor fuses)
SR 80A - 125A - 160A Stack
STA 80A - 125A - 160A Stack
STA 200A Stack
SR / STA 315A Stack
SR / STA 400A - 600A Stack

Instrumentation

We manufacture a number of standard instruments suitable for applications in process control. We can also design and manufacture to your requirements - one offs and small quantities welcome - please contact us with your application.

CB17 single cycle controller

A panel mounted thyristor driver, operating in single cycle burst fire or burst fire control modes.

CU02 staging controller

A load sequencing / staging controller, available in versions for all thyristor control or for thyristor / contactor control

AMOT 130

A combined auto / manual station and over-temperature policeman, suitable for use on industrial furnaces and ovens

Modbus Current and Voltage Monitor

A DIN rail mounted data acquisition module which monitors true RMS voltage and current, and transmits using Modbus RTU protocol

Heater Short Circuit Detector

Heater Short Circuit Detector - A product developed to detect damaging short circuited heating elements, particularly in certain vacuum furnace processes. Available as a 3-zone unit, orfor multi-zone applications in 19" rack mount. Please enquire for further details.

Data Sheets

Extracts from data sheets are available to view in HTML format, with larger pictures, or the entire datasheet is available to view or download in acrobat format (.pdf)

Required to view .pdf files