The Midwest SC Series
1 VA, 2 VA
The UL recognized
SC Series of Midwest donut-type transformer is available in ratios ranging from
50:0.1 to
300:5
Features:
- The Volt Ampere output is 1 or 2 VA.
- Standard leads are 24" in length.
- 600 Volt insulation is standard. A High-Voltage option is available at an additional cost.
- Screw terminals available in place of leads.
Dimensions for SC Series (inches):
Options for the SC Series:
- Special Lead Lengths
- Extra Taps
Installation:
CARE MUST BE TAKEN TO ENSURE THE SECONDARY LEADS ARE CONNECTED AT ALL TIMES when
current is passing through the primary conductor.
Construction:
The Midwest current transformer core is made with grain oriented steel. The core is insulated and then
wound with a secondary winding. The 24" leads are permanently fastened in place and the assembly is
placed in a sealed case.
SC Series Ratio Modifications
Primary Turn Ratio Modification
Formula:
Ka = Kn x Nn/Na
Where:
Ka = Actual Transformer Ratio
Kn = Nameplate Transformer Ratio
Na = Actual Number of Primary Turns
Nn = Nameplate Number of Primary Turns
The ratio of the current transformer can be modified by adding more primary turns to the transformer.
By adding primary turns, the current required to maintain five amps on the secondary is reduced.
(Example: A 100:5 current transformer designed for one primary turn.)
The current ratio between the primary and secondary winding is defined by the following formula:
Ns x Is = Np x Ip
Where:
Ip = Primary Current
Is = Secondary Current
Np = No. of turns on the Primary Winding
Ns = No. of turns on the Secondary Winding
The ratio of the current transformer can be modified by altering the number of secondary turns.
Forward or backwinding the secondary leads through the window of the current transformer will add or
subtract secondary turns respectively.
By adding secondary turns the same primary current will result in a decrease in secondary current output.
By subtracting secondary turns the same primary current will result in greater secondary output.
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To subtract secondary turns, the lead from the X1 terminal should be would through the CT from the same side as H1. |
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To add secondary turns, the lead from the X1 terminal should be wound through the CT from the side opposite H1. |
