W61 N14280 Taunton Ave. Cedarburg, WI 53012
262-377-8585
info@geminicontrols.com
BRIDGES

AC INPUT - AC OR DC OUTPUT

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Typical AC to AC High Power Bridge
   Medium Power AC to AC Bridge 
Large Bridge with Firing Circuit
Click on image for enlarged view

Gemini Power bridges convert AC line power to controlled output, either AC or DC.  The technology is SCR, a type of  the general category of switching devices known as Thyristors.  These designs have proven themselves in applications stretching over a 30 year period, and have been used in the Paper, Steel, Plastic, Printing, Passenger Elevator, Conveyor, Machine Tool and many other industries.

Basic Converters come in three phase configurations, which can be combined to form 6 phase, 12 phase, or even 18 phase configurations, where low harmonic requirements dictate.  With the proper firing circuits, also available from Gemini, the converters can be either one or 2 quadrant in operation, with two converters working together for 4 quadrant performance.


Standard 3-Phase Power Converters
All converters rated up to 480volts input, except 12M04-00015 at 240volts.
600volts input available on special order.

Gemini Part No.

AC

DC

AMPS

Features

12M04-00008

 

X

250

Includes Firing Circuit

12M04-00015

 

X

50

Includes Firing Circuit

12M04-00024

 

X

100

Includes Firing Circuit

12M04-00028

X

 

80

Includes Firing Circuit

12M04-00030-01

X

 

200

Includes Firing Circuit

12M04-00048-01

 

X

500

Includes Firing Circuit

12M04-00049-01

 

X

850

Includes Firing Circuit

12M04-00050-01

 

X

1300

Includes Firing Circuit

12M04-00051-01

X

 

400

Includes Firing Circuit

12M04-00051-02

X

 

400

Without Firing Circuit

12M04-00052-01

X

 

700

Includes Firing Circuit

12M04-00052-02

X

 

700

Without Firing Circuit

12M04-00053-01

X

 

1100

Includes Firing Circuit

12M04-00053-02

X

 

1100

Without Firing Circuit

 

AC to AC Converters
The Gemini AC to AC converters are a series of power controllers based on SCR technology. A converter consists of three separate paths, one for each phase, each one containing two SCRís connected in an anti-parallel, or back to back, arrangement. When a path is connected in series with a load, one of the SCRís conducts current in one direction and the other conducts current in the opposite direction. The load can be resistive, inductive, or the primary of a three phase transformer used to decrease the voltage, such as in electroplating use, or to increase the voltage, such as in applications requiring voltages as high as 300-500 Kvolts.

The control of the conduction is by phase control, with the conducting period of each SCR determined by a firing circuit. Gemini has "unit" firing circuits, where one is required for each of the three paths, with the customer providing the wiring from the firing circuits to the SCRís. Gemini also has a three phase firing circuit, where all three paths are controlled with one circuit. When the three phase firing circuit is used, the power controllers are available with the firing circuit mounted and wired to the group of SCRís. This is generally the preferred configuration, since it avoids mistakes in connection by the customer.

For a single bridge use, the three phase lines are connected to the 3 input terminals and the AC load is connected to the 3 output terminals. Synchronization of firing of the SCRís is obtained automatically when the firing circuit is connected to the cathode and gate of the SCRís. Control is by a dc voltage, and when the 3 phase firing circuit is used, a closed loop regulator is included, to be used or not, depending on the customerís requirements. When multiple bridges are used, the phasing and interconnections become more complex, and the factory should be consulted with details of the power arrangement, so that the proper connections can be determined.

Snubbers are advised to keep the possibility of firing the SCRís by excessive dv/dt to a minimum. The controllers with less than 400 amp rating have these snubbers included and wired in place. For the larger bridges, a series arrangement of a capacitor and a resistor is connected by the customer in parallel with each pair of SCRís. These capacitors should be of the "commutating" variety to avoid problems with the nature of the peak currents that result when an SCR is fired. If the customer is technically qualified, he may choose the values himself. If not comfortable with selecting his own values, Gemini recommends the use of 0.1 mfd, rated at 2000 volts for the capacitor and 200 ohms rated at 50 watts for the resistor, as generally acceptable values for any of the large bridges.

 

Standard Single Phase Power Converters



Pictured above, 72M04-00073

Gemini Part #           Brief Description (for details, contact factory)

12M04-00034                         Single Phase Dual Bridge Converter 240VAC
12M04-00039                         Single Phase Dual Bridge DC Converter 480VAC
12M04-00040                         Single Phase Single Bridge DC Converter 240VAC
12M04-00042                         Single Phase Single Bridge DC Converter 480VAC
72M04-00073                         Single Phase 30 Amp AC Power Converter 480VAC


 

Field Supplies
Gemini Part #           Brief Description (for details, contact factory)

12M04-00003                         Single Phase Power Converter Reversing 240/0/240VAC 0 TO+-200V 20A DC
12M04-00004                         Single Phase Power Converter Non-Reversing 480VAC 0-400V 20A DC
12M04-00043                         Single Phase Power Converter Reversing 300-0-300VAC 0-+/-240VDC 40 AMPS
12M04-00054                         Single Phase Power Converter Non-Reversing 600VAC 0-500V 30A DC
12M04-00055                         Single Phase Power Converter Reversing 300/0/300VAC 0 TO+/-240V 30A DC

 

Click here for the Series 2200, 50-250 Amp Bridges applications manual.
Click here for the Series 2250, 500-1300 Amp Bridges applications manual.

 


 

 

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