NetSure
™
9500 120kW 400V DC Power System
Operation Manual, UM584001200 (Issue AA, April 14, 2014)
Spec. No: 584001200
Code: UM584001200
Model No: 9500
Issue AA, April 14, 2014
[3 of 13]
Power and Control Section
Main AC Input Circuit Breaker: A main AC input circuit breaker is
provided to disconnect AC input power from the power and
control section.
Note:
The main AC input circuit breaker has a system controlled trip
mechanism to trip the breaker if an EPO signal is sent.
Rectifier AC Input Circuit Breakers: Each rectifier has a separate AC
input circuit breaker to disconnect AC input power from the
respective rectifier.
“Output Voltage Present” Indicator: Illuminates green to indicate
voltage is present on the system’s DC output bus.
“Control Voltage Present” Indicator: Illuminates green to indicate
the converter power supply is functioning. (If off when system is in
operation, contact Emerson Technical Support.) (The converter
power supply provides 48V DC for controls.)
“Ground/Insulation Fault Alarm” Indicator: Illuminates red to
indicate a ground fault related alarm condition exists. (See “HRMG
Configuration Ground Fault Detection Circuit Operation” on page
3.)
Warning! It is important to service and remove the
ground fault in the system as soon as the alarm is
indicated.
Distribution Panel Lockout/Tagout (LOTO)
The circuit breakers located on a load distribution panel contain a
bracket which allows the circuit breaker to be padlocked in the off
position.
HRMG Configuration Ground Fault Detection Circuit
Operation
Overview
The ground fault detection circuit in a High Resistance Mid-Point
Ground (HRMG) configuration detects the insulation condition of
the positive and negative DC bus to ground.
If a ground fault is detected, a local indicator illuminates (located
on the front of the power and control section). The ground fault
detection circuit also sends a signal to the ACU+ controller which
activates local and remote controller alarms.
High Resistance Mid-Point Ground (HRMG) Configuration
Benefits
•
Enhanced personnel safety during normal operation by
limiting the available current during accidental line to
ground contact.
•
Continuous bus operation with a single pole ground fault.
•
Limitation of potential arc flash due to limited energy
during an insulation/ground fault condition.
However; it is important to locate and isolate any ground faults
that occur in order to preserve these benefits. The voltages
between the +Bus and –Bus will shift when a ground fault or
insulation breakdown occurs and benefits above will be negated.
In the extreme case, the voltage on an ungrounded pole may be
elevated to 400V DC and present a safety hazard to personnel.
Ground Fault Detection Alarms
The ground fault detection circuit monitors for three different
types of ground faults.
•
Missing Ground: The HRMG grounding lead that exits the
power and control sub-rack is not connected to ground.
•
Ground Fault Alarm: The resistance between the +Bus to
ground OR the –Bus to ground is less than the “Ground
Fault Alarm Limit” parameter set in the ACU+ controller.
The default setting for this parameter is 39.2k©.
•
Bus Voltage Imbalance: Bus to ground voltage
imbalance. The voltage difference between the +Bus to
ground and the –Bus to ground is more than the “Voltage
Imbalance Alarm Limit” parameter set in the ACU+
controller. The default setting for this parameter is 84V.
Note:
The default alarm severity setting for “Bus Voltage
Imbalance” is NA (non-alarmed) and prevents the
condition from being displayed. However, the User
can change the “Bus Voltage Imbalance” alarm
severity setting if desired to display the alarm.
EPO (Emergency Power Off)
The Power Module/Bay has an Emergency Power Off (EPO)
function operated by a remote contact provided by the User.
When the EPO switch is momentarily closed, the main AC input
circuit breaker located on the power and control section of the
Power Module/Bay and the battery disconnect circuit breakers (if
connected to the BATT1 CTRL, BATT2 CTRL, BATT3 CTRL, and/or
BATT4 CTRL connectors located on the rear of the power and
control section of the Power Module/Bay) are tripped open to
isolate the system from all electrical sources. Manual intervention
is required to restart the system. Restart the system by first
turning ON the main AC input circuit breaker then the battery
circuit breaker(s).
Warning
