Guide Form Specification for Medium 

Voltage Motor Surge Protectors 



This specification is for a _________ kV medium voltage three phase motor surge protector that is 

designed to protect medium voltage motors from voltage surges due to lightning and switching events.  

The Motor Surge Protector will be placed on a _______ kV system (Line-Line Voltage) that is 

________ grounded. (ungrounded, solidly grounded, or resistance grounded) The surge protector 

shall come fully assembled and ready for interconnection.  



All exceptions to this specification shall be clearly stated with your bid.  If no exceptions are taken, the 

bid should include the phrase "no exceptions have been taken".





1. Enclosure

1.1	The medium voltage motor surge protector shall be housed in a NEMA 4X stainless steel (with 

B2 finish) enclosure.  The base of the unit shall consist of C2 stainless steel channel for floor mounting 

and skidding into place.



1.2	The cover shall be "L" shaped and gasketed with multiple stainless steel fastening points. All 

corners shall be ground smooth.



1.3	High voltage warning signs and a nameplate showing rating information shall be "blind" riveted 

to the front of the enclosure.  





2. Capacitors

2.1	A low inductance three phase, all-film surge capacitor shall be provided for decreasing the slope 

of impending voltage surges.  The capacitor shall be rated _________ micro-farads to ground and have 

a _______ voltage rating. 



2.2	The capacitor shall be equipped with discharge resistors that reduce the capacitor voltage to 50 

volts in 5 minutes when disconnected from the source.  



2.3	The surge capacitor shall be capable of operating in the temperature range between -40 degree 

Fahrenheit and +115 degree Fahrenheit.





3.  Surge Arrester

3.1	The medium voltage motor surge protector shall be equipped with three heavy duty distribution 

class lightning surge arresters for limiting the crest of impending voltage surges to safe values.



3.2	The surge arrester shall be silicone rubber housed, and shall utilize MOV blocks incorporating 

resistance graded gap technology.  The arresters shall comply with ANSI/IEEE C62.11 standards.



3.3	The voltage rating and MCOV shall be appropriately rated for the system voltage and 

grounding as specified above.





4. Connections

4.1	The unit shall come fully assembled and ready for interconnection.  Standoff insulators shall be 

provided for termination of customer phase conductors.  Termination points shall accommodate 2 AWG 

wire size.





5. Submittals

5.1	Upon issue of a purchase order, the supplier shall provide 3 copies of approval drawings.  The 

submittals shall include:



- Installation Instructions

- Single Line and three line diagrams

- Pad and cable entry drawings 

- Drawings showing component layout

- Data sheets for all internal components





6. Bid Requirements

6.1	Supplier must state all exceptions in the Bid.  If no exceptions are taken, the supplier must state 

that there are no exceptions.





7. Acceptable Product & Suppliers

7.1	Suppliers must offer a minimum 2 year warranty and have available extended warranty 

programs.



7.2	Supplier must have a licensed professional engineer on staff that has a post graduate degree in 

electric power engineering.  Credentials shall be supplied upon request.



7.3	Supplier must show that they are a regular supplier of medium voltage motor surge protection 

equipment.



7.4	Acceptable Manufacturer and Product: 



MSP? by Northeast Power Systems, Inc. (NEPSI)