Shop All Staco Variac Variable Transformers and Test Sets

Selecting the Staco Variable Transformer best suited for your specific requirements is easy once you make the following basic determinations: 

Input:

1. Line Voltage
2. Single or Three Phase
3. Frequency

Output:

1. Voltage
2. Amperage
3. kVA

To assist you in making the proper selection, an explanation of Staco's standard numbering system is described below. 

The Staco Product Numbering System

The basic single units (open construction) are identified by 3 or 4 digits, i.e., 501-C, 1010B, 5021, etc. 

• The first two digits designate the current
• the third, voltage
• the fourth is simply a decimal locator.

1.  In a 3 digit number, the first digit indicates amperes, the second indicates the additional fraction of amperes, the third indicates voltage.  For example, with the 501-C the 50 indicates 5.0 amperes and the 1 indicates a 120 volt line.

2.  In a 4 digit number where the third digit is one, the first two digits indicate amperes, the third designates 120 volts.  For example, with the 1510, the 15 indicates 15.0 amperes, the 1 indicates 120 volts, and the 0 is a decimal locator.

3.  In a 4 digit number where the third digit is 2, the first two digits are twice (approximately) the amperes, and the third indicates 240 volts.  For example, with the 6020, the 60 indicates that the amperage is approximately 2X the current rating (about 35 amperes), the 2 indicates 240 volts, and the 0 is a decimal locator.

Prefixes and Suffixes

Staco Variable Transformers are available in many different configurations.  These other models can be identified by adding the following prefixes or suffixes to the basic 3 or 4 digit numbers.

Prefixes:

    "5"  etc. = speed in seconds of travel,

    "M" = motorized

    "3PN" = 3 prong cord and receptacle

    "J" = Isolated unit

    "L" = L series (fully enclosed)

Suffixes:

    "2" through "27" = ganged units (2=2 ganged, etc.)

    "A" = Ammeter

    "C" = Cased

    "D" = Delta connected

    "E" = NEMA 1 drip-proof enclosure

    "G" = Military

    "H" = 400 Hertz

    "K" = Less knob

    "N" = Less dial

    "P" = Parallel connected

    "PS" = Parallel series, connected

    "S" = Series connected

    "T" = Terminal box

    "V" = Voltmeter

    "W" = Wattmeter

    "Y" = Wye connected

*NOTE:  When part numbers end in B or -B, the B is not considered or used as a suffix.

120 Volt Series Unit Ratings

Series	Max. Constant Current	Amperes* Constant Impedance
171	1.75	2.2
201	2.0	2.5
221-B	2.5	3.2
291	3.0	3.5
501-B	5.0	7.0
1010B	10.0	13.0
1210B	12.0	15.0
1510	15.0	20.0
2510	25.0	30.0
5011	50.0	--
6011	60.0	--

 

240 Volt Series Unit Ratings

Series	Max. Constant Current	Amperes* Constant Impedance
252	0.8	1.0
1020B	3.5	5.0
1220B	5.0	7.0
1520	9.5	12.0
2520	10.0	13.0
5021	28.0	--
6020	35.0	--