MIEE – Chapter 22 – Mobile Generator Link Box (MGLB)
22 Mobile Generator Link Box (MGLB)
22.1
Background
Mobile generators are used throughout Defence in various forms to ensure continuity of power
supply during times of extended power outages or for deployable sites where there is a need to
connect deployable generators and mains power supply may be unavailable. This policy describes
the Defence requirements for Mobile Generator Link Boxes (MGLB) used to connect mobile
generators to building and equipment loads.
MGLB are switchboards provided to enable the safe and convenient connection of mobile
generators, either hire or Defence owned generators, to building and equipment loads. MGLB can
be required for deployable equipment hardstands and other important facilities when the expense of
a permanent Local Emergency Generator (LEG) cannot be justified. MGLB are also provided for
each LEG installation to facilitate continued generator support when the LEG is unserviceable, or
undergoing extended maintenance.
22.2
Performance Objective
The objective of this policy is to:
a)
facilitate the safe and convenient connection of mobile generators, and
b) provide a consistent mobile generator connection interface.
22.3
Technical Requirements
The MGLB can be either wall mounted or free standing. It shall be located adjacent to the mobile
generator hardstand, externally to the building where wall mounted, within reasonable access of the
generator to minimise cabling. The MGLB and hardstand shall be in a position that ensures the
MGLB and the mobile generator will not obstruct access or egress to the facility and in a manner
that ensures noise or vibration from the generator will not have an adverse impact on the facility.
The generator hardstand or generator set down area shall include suitable environmental control
provisions to accommodate the generator and the required fuel storage. This hardstand or set down
area shall be suitably located so that it is directly accessible by truck.
The typical MGLB arrangements are shown in Figure 22.1. The MGLB shall be provided with the
following:
a)
5 suitably sized reusable lugs for the connection of power cabling to the generator such as
ALM “KULUG” type Q or QA, or similar;
b) Fail safe type phase rotation indicator (i.e. indicates both correct and incorrect generator
supply phase rotation) and voltmeter with phase selector switch;
c)
Suitable bottom cable entry for the generator connecting cables.
The MGLB connection arrangement shall ensure the weather proofing of the connections, and shall
prevent accidental contact of personnel with live parts, in all circumstances; and 230V socket
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MIEE – Chapter 22 – Mobile Generator Link Box (MGLB)
outlet, where mains power is available. The mobile generator link box shall be provided with a
suitable 230V socket outlet to allow connection of the generator auxiliaries such as battery charges.
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Chapter 22 - MGLB
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MIEE – Chapter 22 – Mobile Generator Link Box (MGLB)
NOTE:
ENCLOSURE MANUFACTURED FROM 2mm SHEET STEEL
FOLDED AND FULLY WELDED. ALL WELDS GROUND SMOOTH.
IP56 (MAIN CABINET DOOR).
PHASE ROTATION
AND VOLTMETER
ENCLOSURE FINISH: EXTERNAL - PALE GREY POWDER COAT .
METER SELECTOR
SWITCHES
INSULATED POST TO
SUPPORT
BUS BAR ARRANGEMENT
QLUGS
LOCKABLE "T" HANDLE
604 TUMBLER
1000x1000 CONC. N25 SLAB WITH F72 FABFIC.
FIX LABELS AS DETAILED TO OUTSIDE LINK BOX.
REMOVABLE ACCESS PANEL
TRAILING CABLE SUPPORT BAR
MOBILE
GENERATOR
LINK BOX
2 OFF KNURLED
CAPTIVE SCREWS
MINIMUM
GENERATING
CAPACITY FOR
OPERATION
xxxkVA
CABLE ACCESS HINGED COVER
TRAILING CABLES
CONCRETE FOOTING
2 X 100mm HD uPVC CONDUITS
FRONT VIEW
SECTION
TYPICAL GROUND MOUNTED ARRANGEMENT
BUS BAR ACCESS VIA
REMOVABLE PANEL
WEATHERPROOF SEAL
BETWEEN WALL/PANEL
ANGLED ROOF AND RAIN
GUTTER
INSULATED POST TO SUPPORT
BUS BAR ARRANGEMENT
PHASE ROTATION
AND VOLTMETER
METER SELECTOR
SWITCHES
TRAILING CABLE SUPPORT BAR
REMOTE
STOP/START
CONTROL LINKS
(DIN RAIL TERMINAL
STRIP)
FULLY WELDED SECTION
BETWEEN
EXTERIOR PANEL BUS BAR
TRANSITION THROUGH WALL
QLUGS
CABLE ACCESS HINGED
COVER
2 OFF KNURLED
CAPTIVE SCREWS
TRAILING CABLES
FRONT VIEW
SECTION
TYPICAL WALL MOUNTED ARRANGEMENT

Figure 22.1: Typical Mobile Generator Link Box Arrangements
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Chapter 22 - MGLB
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MIEE – Chapter 22 – Mobile Generator Link Box (MGLB)
22.3.1 Socket Outlets
Should a plug/socket arrangement be required by the end users to connect the mobile
generator, the socket shall be mounted externally on the link box and shall be provided in
addition to the typical link box connection arrangements of Figure 22.1 above. The purpose of
the plug/socket arrangement is to provide additional flexibility for the connection of the
mobile generator and shall in no way interfere with the operation of the link box as described
in above. Suitable instructions shall be provided in the link box on the use of the socket outlet
in the form of an engraved label. The socket outlet shall be clearly labeled to prevent
improper use.
22.3.2 Main Switchboards
The main switchboard shall be provided with an appropriate changeover switch to connect the
facility or equipment either to mains supply or to the mobile generator supply as required.
The configuration of the changeover switch shall ensure that the mobile generator can be
safely connected whilst mains supply remains available to the equipment or facility. The
changeover switch shall have three resting positions which shall be labeled “Mains”, “Off”
and “Mobile Generator”. Maximum demand indicators shall be provided in the main
switchboard to facilitate the assessment of the required generator size for the facility or
equipment.
22.3.3 MGLB External Labeling
The link box shall include an external label “Mobile Generator Link Box” as well as an
internal label “Minimum Generator Size for Operation XXXKVA” (the generator size
required shall be determined during the design stage and shall be based on the requirements
set out in the design brief). MGLBs incorporating the main switchboard shall also be provided
with a switchboard label and circuit schedule in accordance with Defence Low Voltage
Distribution Pillars and Switchboards Labelling and Numbering requirements.
22.3.4 Local Emergency Generator Installations
In addition to the above requirements, MGLB used for LEG applications also require the
control circuit connections necessary to allow automatic starting and stopping of the mobile
generator (in lieu of the LEG) through the LEG control system. The control connection shall
be provided in a suitable location within the MGLB to allow termination of the control cable
from the mobile generator.
The LEG control system shall be suitably arranged to facilitate the remote operation of the
mobile generator. To achieve this, the LEG control system may need to monitor the position
of the transfer switch to determine when the mobile generator has been selected. The control
system shall in no way inhibit the use of manual start generators.
For LEG applications, the main switchboard or generator switchboard shall be provided with
an appropriate manual transfer switch that allows connection of the LEG or the mobile
generator. The transfer switch shall have an off position to allow both the LEG and the link
box to be isolated (to allow the mobile generator to be safely connected or the LEG to be
isolated for maintenance). The manual transfer switch shall be suitably labelled (e.g. “LEG”,
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MIEE – Chapter 22 – Mobile Generator Link Box (MGLB)
“OFF” and “Mobile Generator Link Box”); the switch position shall also be monitored by
the LEG control system. Maximum demand indicators are to be provided in the LV
switchboard to facilitate the assessment of the required mobile generator size for the facility
where the intelligent meter cannot provide the required data.
It shall be possible to use the LEG dummy load, where provided with the mobile generator.
22.3.5 Deployable Equipment Sites
MGLB provided for deployable equipment hardstands shall be incorporated as part of the
Main Switchboard (MSB). The MGLB/MSB shall be located adjacent the generator hardstand
and the deployable equipment hardstand in a suitable manner to minimise cabling between the
switchboard and generator, and the switchboard and equipment cabin, respectively.
Mobile generators used for deployed equipment sites, such as deployable aircraft navigation
aids, may have automatic start ability. MGLB provided for these deployed equipment sites
should consider the inclusion of an automatic changeover facility to automatically start and
connect the mobile generator to the intended load on a power failure. The system shall be
suitably configured to allow connection of either automatic or manual start generators. The
MGLB for deployed equipment sites needs to incorporate the main switchboard element,
cable protection and suitable equipment connection arrangements.
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Chapter 22 - MGLB
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