When current transformers are operated open circuited, extremely high voltages can be generated with resultant damage to equipment and personnel.
Before removing a load such as a meter or relay, the CT should be short circuited using a shorting block. The ungrounded secondary of a voltage transformer and the line side of the power supply should be fused before connecting to a device such as a meter or relay. ShortingBlocks.com manufactures several models of shorting and test blocks.
All products are CSA and UL approved.
If current transformers are operated open circuited, extremely high voltages can be generated with resultant damage to equipment and personnel.
Consequently, before removing a load such as a meter or relay the CT should be short circuited.
An easy, efficient and convenient method of doing shorting CTs is through the use of a shorting terminal block which automatically short circuits the instrument transformer when the load is removed.
The WEC-100 series of shorting blocks as supplied by Langford & Associates are assembled from Entrelec components and mounted on a standard DIN rail. These shorting blocks consist of a base element to which the current transformer is wired and a plug element to which the load wired. The base has a pressure plate terminal and the plug has a pin, which is crimped onto the wire.
When the plug is inserted into the base the load is connected to the CT. When it is desired to disconnect the load, the plug is removed and the CT is automatically short circuited before the disconnection is completed.
The units are suitable for up to #12 AWG wire. Marking strips are included for both the plug and base as well as tie wraps for trimming the wire into the plug.
Jumper bars allow ease provide a simple connection if a common point is required.
|Catalogue Number||Connection Method||Rating Price|
|WEC 104-12-J||Current Plug (4 pole) 5A 150V||$130.00|
|WEC 103-12-J||Current Plug (3 pole) 5A 150V||$120.00|
The WIV 204-N/600 may be used when it is desired to have a direct connection from a 480 VAC or 600 VAC source, either Wye or Delta to an instrument.
Connection is made directly from the Voltage source to be monitored, through the fused switches into the instrument.
A fused switch and neutral block (non fused, non switched) are also provided for the 120 V power source for the instrument.
The unit is mounted on a 150 mm DIN rail. 2A fuses are supplied.
We carry a complete line of low and medium voltage Current Transformers including:
We carry a complete line of low and medium voltage Potential Transformers including:
Control and Power wire termination. Short circuiting versions for meter servicing.