Siemens Breaker Settings

Issue:

Siemens Breaker Settings

Resolution:

Siemens Breaker Information

See attached file(s) for information on setting the breaker trip element(s).

• Sensitrip / Sensatron Breaker: (click here)
  • Photo of what the breaker looks like (click here).
• VL Breaker: (click here) and (click here)
  • 460 VAC chiller applications, you will need to turn up the Ii setting to a higher value6-8 times compressor FLA.

  • DO NOT adjust the Ir and tr settings (these are set by Benshaw but DO NOT effect initial inrush current which is the Ii setting).

• FD Breaker: (click Here)
• JD & LD Digitial Trip/Sensi-Trip Breaker: (click here)
• JD & LD Sentron Breaker: ( click here )
• ED Breaker: ( click here )
• Thermal / Temperature De-rate Information: ( click here )
  • High Ambient Temperature
  • High Altitude
  • Unusual Operating Conditions

.

CGAM Chillers ONLY:

• 200 - 230 VAC application: Thermal Magnetic Breakers are installed for each compressor as motor protection. Adjust Thermal Mag breakers to click/position 3 (third notch) or set at best location as determined by attached literature to prevent nuisance trips.
  • Factory testing shows this position (the third position) will adequately start compressors in most applications without increased risk to FUSITE (motor terminals).
• 460 VAC applications: Standard Breaker is a fixed trip breaker.
  • Special application of VL breakers; manufacturer inability to supply Fixed Trip Breakers (see attached information for details on setting VL breakers.)

Notes:

• The breaker settings are set at minimum from the factory.
• It is customary for manufactures and distributors to send breakers out with ALL settings a minimum (Siemens does - all settings at minimum). The settings should be adjusted in coordination with the end customers site specific conditions to avoid potential liability.
• Trane chillers with integrated Starter Controls provide internal motor protection. It is NOT necessary to rely on Circuit Breakers for motor protection. It is possible that the minimum Circuit Breaker settings may be to sensitive and prematurely open the protective device. In those instances, it is customary to increase / adjust circuit breakers so false conditions do not trip the breaker.
• Without taking direct liability to breaker setup; one could take a guess and then calculate the maximum current expected - different based on solid state starter (260% of RLA), Y-D starter (refer to LRA Y-D, transition will create spike as well) or Across the Line (ATL - up to 600-850% based on motor efficiency / KVA code). Then looking up the trip adjustment ranges for the specific breaker, then set 5-10% above expected.
• Other than the previous discussion - trial and error - if it trips increase it a click or notch at a time, until it stops; careful to prevent exceeding starts per hour during testing. (Thermal Mag breakers have adjustment ranges "Lo-2-4-6-8-HI" for example a 225A breaker notes on the breaker the adjustment range from 1100 to 2500 amps, which is 480% to 1100%).

Breaker types supplied from Siemens (via Benshaw):

 CB Guide - Form Specifications:  ( click here ) 

• Molded case switches; there are no adjustments that can be made, no overload or low fault current protection is provided.
• Circuit Breakers (Thermal Magnetic), they have non adjustable time-delay thermal trip elements for overload protection and adjustable instantaneous magnetic trip devices for short circuit protection. The adjustable instantaneous setting can be varied by 8 selectable ranges. For example; a 600 amp breaker set on the low setting would trip at 3,000, +-25%(~5 x trip element of 600) amps, on high - 6,000, +-20% (~10 x ) amps. Only default I could give on setting this is to find the motor's locked rotor current rating (delta) and set it slightly higher than that. Again the problem could be one of coordination - does the end user have fuses that may open or other circuit protectors that will open prior to our disconnect tripping under fault conditions?
• On the Solid State Breakers (Sensitrip) there is much more to setting up the breaker. The customer should have had a particular reason in mind to purchase one and without a coordination study one guess is as good as any other. I can not give any general guidelines without site specific knowledge, they need to refer to their system engineer or consultant for proper set up of the breakers.

Trip Unit Questions

Q: Do electronic trip circuit breakers like the Siemens SENSITRIP and the SB breakers come pre-set from the factory for a particular application?

A: The electronic trip units on the Siemens circuit breakers are not set for particular applications, but they are shipped with the trip adjustments set at the minimum positions. Due to the wide variety of systems and loads it is impossible for Siemens (or Benshaw...or Trane) to pre-set circuit breakers for a specific application. Ideally a Coordination Study should be conducted for the specific system requirements and would list the needed settings for all of the over current protective devices in the system. If a coordination study has not been performed, a knowledgeable user with Siemens Time Current Curve software can determine the basic settings for the breakers. This software is easy to use and provides the tools needed to select settings, to determine coordination between breakers at each level in the system, and to provide a printout of the time current curve and a list of settings. This software is available free of charge from Siemens web site. To access this site, click on the link Siemens Time Current Curve software.

Other Question/Problem/Cause Statements:

• Siemens Breaker Settings
• Breaker tripping
• How to set-up the Siemens breaker
• Benshaw Solid State Starter Fault Code F27
• SSS F27
• Solid State Starter Fault
• VL Breaker
• ED Breaker
• JD Beaker
• LD Breaker
• FD Breaker
• Circuit breaker is tripping
• How do I set the dials on the circuit breaker

Facts:

• New chiller start-up.
• Water-Cooled Chiller (Pueblo)
• Air-Cooled Chiller (Pueblo)