GE Industrial Solutions Entellisys 5.0 Administrator Manual - Manual (Page 29)

Administration 29
5
5.3 Administration
When enabled on a breaker or group of breakers, Reduced Energy Let-Through mode uses an
independent set of over current protection settings. The RELT mode is usually turned ON when
people will be near the energized equipment or near downstream equipment. The RELT settings
are typically set at more sensitive levels than what is used in normal operation. These more
sensitive settings can pick-up and operate faster than the normal settings and therefore
minimize the incident arc energy during an arcing fault.
To place breakers into RELT mode an operator must meet the following criteria:
• Have a user ID that allows RELT on/off access
• Enter the corresponding password to the User ID each time he enables or disables RELT
Therefore, the administrator of the Entellisys system must consider how they want to set up
User Ids and related permissions. It is recommended that each individual have their own User ID
and related password instead of a group User ID and password that a number of people use.
This is so each individual can enable/disable RELT "keys" independent of each other.
For example, if Ted places a breaker in RELT and an hour later Joe wants to place the breaker in
RELT, each can do so independently. Then, when each is finished (at different times) they will turn
their RELT off, and RELT will remain in effect until the last person is finished. In contrast, if a group
User ID and password is used, Ted would turn it on, Joe would see that it was on and not put it
on. Ted could turn RELT off not knowing that Joe still wanted it on. The User ID permissions and
set-up is the responsibility of the site's Entellisys administrator and care should be taken in
determining what suits the site.
The site administrator must also consider what RELT (topology 0) settings to select. Typically the
settings are more sensitive than 'normal' protection settings. When RELT is used with Entellisys
dynamic zone selective interlocking and bus differential, selectivity with upstream breakers can
be achieved while providing faster than 'normal' settings response times to arcing faults.
Although the RELT (Topology 0) settings are user-adjustable, the values described in the
following sections are examples of the most sensitive settings and minimum delay bands.
See DEH 501 System User’s manual for more information about settings.