Application Guide

System Application Guide SAG584000300
NetSure™ 4015 30kW 400V DC Power System Issue AB, April 5, 2013
Spec. No. 584000300 (Model 4015-X003)
Page 17 of 32
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ACCESSORY DESCRIPTIONS
DC Load Distribution Devices
DIN-Rail Type Load Circuit Breakers
Features
Each distribution position in the load distribution sub-rack is factory furnished with a distribution block and
cover (for ease of adding circuit breakers in the field). When circuit breakers are specified on initial order,
the factory replaces the distribution block and cover with the specified circuit breaker. When breakers are
ordered separately for field installation, this same procedure must be performed. See UM584000300
(Operation Instructions) for details.
Each circuit breaker is a 2-pole device and occupies one circuit breaker mounting position in the load
distribution sub-rack. The load distribution sub-rack has nine (9) circuit breaker mounting positions.
Restrictions
Load should not exceed 80% of device rating.
Only breakers specified in Table 1 are to be used. NO substitutions are acceptable.
Ordering Notes
1) Order circuit breakers as required per Table 1.
Output Load Circuit Breaker Selection
Refer to the following guidelines in addition to following local codes and practices.
Systems with Batteries
a) Define the power requirement of circuit to be protected (ex. 5000W) [assume constant power
electronic load].
b) Determine the minimum system voltage per the system design parameters (including any voltage
drop accounted for to the load). This will generally occur at the end of battery discharge and this
voltage value should not exceed the minimum rated operating voltage of devices on this circuit.
c) Divide circuit power in step a) by the voltage determined in step b). This represents the maximum
discharge current that the breaker must accommodate.
d) Round up to the next breaker size.
e) Check: Divide maximum circuit power in step a) by the normal system operating or float voltage (e.g.
378V DC). This is the normal operating current. Multiply this value by 1.25 to account for breaker
derating factor per the NEC. Round up to the next breaker size.
f) Breaker size required is the larger of step d) or e).
Example
5000W / 260V DC (minimum device voltage) = 19.2A, round up to 20A breaker.
Check: 5000W / 378V DC = 13.2A x 1.25 = 16.5A, round up to 20A breaker.
Systems without Batteries
a) Define power requirements of circuit to be protected (ex. 5000W) [assume constant power electronic
load].
b) Divide circuit power in step a) by the system operating / float voltage (e.g. 378V DC). This is the
normal operating current. Multiply this value by 1.25 to account for breaker derating factor per the
NEC. Round up to next breaker size.
Example
5000W / 378V DC = 13.2A x 1.25 = 16.5A, round up to 20A breaker.
Note: Select wire gauge per Table 8 for each circuit. Note that Table 8 is only for two (2) conductors per
conduit. For more than two (2) conductors per conduit, establish a current value equivalent to 80% of
the breaker size determined from the formula in the above procedures to calculate the wire sizes per
the NEC. Do not exceed the ratings of the device / load when coordinating with a system operated
with battery back up.