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Economical three-phase power switching

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article image Eurotherm’s power switching module.

EUROTHERM's TC2001 two-leg three-phase power switching module offers an economical solution for controlling three-phase resistive and inductive loads up to 1650A at up to 690V ac.

Utilising two leg control in three-phase star or delta loads can provide up to 40% savings against full three-phase switching systems.

The TC2001 provides a compact, two-phase thyristor power switch for electrical heating applications from 100 to 690 volts, 60 to 1650 amps.

The TC2001 uses two thyristor pairs to switch the supply to two limbs of a three-phase, three-wire star or delta load. The individual power switching elements can also be used as power switching control for two independent single-phase loads if required.

The TC2001 can operate from logic or analogue inputs as well as being able to be operated manually via an external potentiometer. It is suitable for controlling inductive loads including three-phase transformers as well as resistive loads with low temperature coefficient.

The firing mode is either burst firing with adjustable delayed firing angle on first cycle or logic on/off firing all with zero voltage switching to eliminate noise emissions. The burst firing modes provide a delayed firing of the first cycle for use with inductive or transformer loads.

Due to the reduced component complexity, the TC2001 provides space-efficient power control for three-phase loads, plus switching only two phases reduces by 33% the power dissipated by the thyristors.

The compact size and lower dissipation mean that the control cubicle too can be more compact and less expensive. The TC2001 also offers better temperature control than mechanical contactors, which cannot be rapidly switched for both thermal and mechanical lifespan reasons.

The resulting long cycle times when utilising mechanical contactors causes large temperature fluctuations. The shorter cycle times possible with the TC2001 allows power to be delivered exactly as it is needed to maintain a constant temperature.

When used with analogue inputs the TC2001 also compensates for supply variations to hold load power constant and further reduce temperature changes.

Low maintenance costs are obtained when compared against mechanical contactors in electrical heating applications which can switch millions of times every year, resulting in relatively short lifetimes.

The TC2001 has no moving contacts so will last almost indefinitely. Additional application savings are obtained as the short on/off cycle times cause less heater expansion and contraction and reduce breakage due to fatigue and thermo-mechanical stress.

Overall savings include reduced costs of new heaters, contacts, installation and lost production, in addition to a reduction of scrap.

Designed for use in real world industrial applications, for protection against surges and overload, robust thyristors are utilised in-place of triacs with extra MOV and RC protection.

Designed to be over-specified, the TC2001 is fully rated to its design maximum operating temperature of 50°C, with de-rating up to 60°C also available.

The solid state switching is also completely silent, allowing the modules to be utilised in applications where noise pollution from large contacts would be an issue. DIN rail mounted, the TC2001 is simple to install and fast to commission, being ready to operate out of the box.

The TC2001 is fitted with a bar graph for each switching element, providing simple indication of the power percentage firing of each element. It can also be fitted with current transformer feedback and a partial load unbalance alarm.

All units are manufactured within ISO9001 certified production environments, and are designed to comply with all relevant international standards (including CE in Europe and UL in Canada and the USA), allowing users to export machines containing the TC2001 throughout the world.

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