| Isolation Transformers are the most basic types of transformers used in industry today. They are also known as linear transformers. They provide electrical "isolation" between the primary and secondary windings. Normally they have a primary with more than one secondary winding. They reduce electrical noise between primary and secondary. Electrostatic shielding can be added to further increase isolation. These can be designed in single phase or three phase. |
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| Step-up/Step-down Transformers are used to change the incoming voltage. They either increase it (step-up) or decrease it (step-down). They are often designed to do both to accommodate worldwide voltage requirements in a single transformer unit. Nicollet has manufactured single phase units from 25VA to 20KVA and three phase units from 50VA to 50KVA. Nicollet builds to custom electrical requirements and does not compete with "Off the Shelf" or standard catalog items. |
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| Control Transformers are used primarily for step-down to power low voltage circuits and/or accessories. These are commonly used in many types of industrial equipment. Nicollet can build these units from 25VA on up. |
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Inverter Transformers closely resemble pulse and wideband transformers because their proper function depends on the input switching circuitry used. This circuitry typically applies a non-sinusoidal waveform that is reflected at the output. Input waveshape, switching frequency and voltage are the minimum information required for design. Any size over 100VA can be manufactured. |
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| Rectifier Transformers are used to step-up or step-down ac voltages for rectification and filtering. Input voltage and frequency establishes the primary rating while the secondary ac voltages and currents are determined by the dc requirements. Nicollet can manufacture single phase units from 25VA to 20KVA and three phase units from 50VA to 50KVA. |
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| Autotransformers like isolation
transformers, are used to step-up or step-down voltages. However,
autotransformers have only one winding and therefore no electrical
isolation from input to output. The advantage of using an auto wound
transformer over an isolation transformer is that they are smaller,
lighter and less expensive. Typical applications include motors,
heaters and other non-sensitive load requirements. Nicollet can build
these from 100VA to 40KVA single phase and three phase units to 75KVA. |
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Ferroresonant Transformers also known as
constant voltage transformers (CVT). Ferroresonant designs allow the
primary voltage to vary while the output voltage is held constant.
Additionally, ferroresonant transformers can be designed to provide
various degrees of current limit. Standard output ferros are typically
used voltage regulating rectifier transformers. Sine-wave ferros use a
harmonically compensated secondary winding, producing a waveform that
is nearly sinusoidal. Ferroresonant inverter transformers are found
primarily in uninterruptible power supplies. Nicollet offers ferroresonant designs from 25VA to 10KVA in 50HZ, 60HZ and 50/60HZ.
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| Current Limiting Transformers limit the output current during an overload condition by reducing the output voltage. In fact the output voltage can be designed to drop to zero volts when a short circuit occurs (without damaging the transformer). Current limiting transformers are commonly used to provide protection in high voltage circuits but can be used in low voltage applications as well, generally from 10VA to 1000VA. |
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| Chokes , also known as inductors, are commonly used in inverter, power supplies, UPS, welders, variable speed drives, and motor starters. |
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| Filter chokes are used to filter electric circuits. They are often used with capacitors to reduce ripple in DC applications. It is common practice to design filter chokes with an air gap in the core to prevent dc saturation. The air gap, size of the core and number of turns depend on the inductance desired, direct current in the winding and the ac voltage across the winding. Sizes available are typically two pounds and larger. |
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| Swinging chokes are filter chokes designed with two inductance ratings at two current levels. In swinging chokes the core is purposely allowed to saturate at higher values of direct current and are non-linear. They are characterized by smaller air gaps, more turns and larger size. Sizes available are typically two pounds and larger. |
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AC chokes are also referred to as AC reactors. They are primarily used to limit current in applications where temporary overloads and short circuits must be accommodated without damage. The reactor will have a nominal rms current rating and a maximum current rating. The rms rating is based on the duty cycle of the maximum and the normal operating current. Sizes available are typically two pounds and larger. |
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