
Description
Simplex Merlin Load Banks are the 
new standard for advanced design in 
Portable Load Banks spanning the 
capacity range of 100–400KW. The 
Merlin is a dual voltage (240/480v), fi ne  
load step resolution, fully instrumented 
Portable Load Bank intended for 
small-medium capacity shop or fi eld  
use by engine generator dealers and 
service shops for maintenance, testing 
and performance proving of engine 
generator sets, UPS and other power 
systems in the 50–400KW range. The 
Merlin is available in discrete model 
sizes of 100KW, 150KW, 200KW, 
250KW, 300KW, 350KW and 400KW.
The Merlin control panel includes 
test instrumentation, load application 
switches, operation indicator lights and 
fan/control power switch. The Load 
Bank includes rugged “Powr-Web” 
load elements, load control contactors, 
branch circuit fuse protection of the 
load elements, high temperature power 
wiring, cooling fan with circuit breaker, 
control power fuses. The Load Bank 
is protected against fan failure, high 
intake air temperature, high exhaust air 
temperature, and overvoltage. The unit 
includes a 12’ connection cable set.
MERLIN
100KW - 400KW Load Bank
Merlin Load Banks are built on a formed 
and welded steel chassis that is both 
rugged and lightweight. For fl exible  
portability, the Merlin includes casters, 
lifting eyes and forklift channels. Airfl ow  
through the unit is horizontal with 
cooling provided by a cast aluminum 
airfoil type shrouded propeller fan.
Features
• Exceptionally rugged, all welded, 
formed steel chassis
• Hinge-open control section door
• Lifting eyes, forklift channels and 
casters
• Moving handle
• “PowrWeb” Load Elements
• Branch circuit fuse protection
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Onsite 
®

MERLIN
100KW - 400KW Load Bank • Page 2
Powr-Web Resistive Load 
Element
Description
Simplex Load Banks utilize the “PowrWeb” Load Element (a UL Recognized 
Component). The “Powr-Web” is an 
advanced design, air-cooled power 
resistor specifi cally designed for  
application to load bank systems. The 
“Powr-Web” is conservatively operated 
at half the maximum temperature rating 
of the alloy and features a short-circuitsafe design based on continuous 
mechanical support of the resistor by 
high temperature, ceramic clad stainless 
steel rods.
Construction
®
• Precision calibrated to specifi c ohmic  
value 
• All load elements are continuously 
supported by vibration resistant, 
ceramic clad, stainless steel throughrods.
Specifi cations
• Alloy: FeCrAl
• Maximum continuous temperature 
rating: 1920°F 
• Maximum operating temperature as 
applied in Load Bank: 1080° F 
• Cool down time from operating to 
ambient temperature is 10 seconds.
Branch Circuit Fuse 
Protection
The load of a resistive load bank 
consists of a dense array of open, 
uninsulated power resistors mounted 
within a cooling air stream. Since 
the elements are electrically live, it is 
possible for a foreign object to penetrate 
the element array and create a short 
circuit of adjacent elements or a short to 
ground. Since the elements are densely 
packed, it is possible for a short circuit, 
once started, to rapidly propagate 
through the entire element array. As 
a load bank represents a relatively 
large amount of power concentrated 
within a relatively small volume, a selfpropagating, cascading short circuit 
would have catastrophic results.
Simplex virtually eliminates the 
dangers of short circuit through the 
use of branch circuit fuse protection of 
the load elements. Per NEC 110-10, 
protective devices shall clear a fault 
without “extensive damage” to the circuit 
components. A Simplex Load Bank is 
divided into branch circuits of not more 
than 50 KW each.
Simplex, Inc. 
5300 Rising Moon Road 
Springfi eld, IL 62711-6228
217-483-1600 
Fax 217-483-1616 
www.simplexdirect.com
© 2012 Simplex, Inc. All Rights Reserved. 
Printed in the USA • 1103-03.01 
Design subject to change without notice.

Insight      
Onsite 
MERLIN
100KW - 400KW Load Bank • Page 3
KW , 1.0 P.F. COOLING FAN LOAD STEPS
240/480V,
Model
Merlin 100 100 75 63 67 0.75 120V/240V, 1-ph. 6000 5, 10, 10, 25, 50
Merlin 150 150 112 94 100 .75 120V/240V, 1-ph. 6000 5, 10, 10, 25, 50, 50
Merlin 200 200 150 125 134 1.5 120V/240V, 1-ph. 6700 5, 10, 10, 25, 50, 100
Merlin 250 250 188 157 167 1.5 120V/240V, 1-ph. 6700 5, 10, 10, 25, 50, 50, 100
Merlin 300 300 225 188 200 1.5 120V/240V, 1-ph. 6700 5, 10, 10, 25, 50, 100, 100
Merlin 350 350 262 219 233 3.0 240/480V, 3-ph. 8000 5, 10, 10, 25, 50, 50, 100, 100
Merlin 400 400 300 250 267 3.0 240/480V, 3-ph. 8000 5, 10, 10, 25, 50, 100, 100, 100
3-phase
Fan/Control Power
User selectable, internal/external
Internal Power
Merlin 100, Merlin 150: 
120V, 1-ph, 2-wire, 60Hz 
240V, 1-ph, 3-wire, 60Hz 
208-240V, 3-ph, 4-wire, 60Hz 
Optional: 416-480V, 3-ph, 3-wire, 60Hz 
Optional: 50Hz Voltages
Merlin 200 through Merlin 300: 
120V, 1-ph, 2-wire, 60Hz 
240V, 1-ph, 3-wire, 60Hz 
208-240V, 3-ph, 4-wire, 60Hz 
416-480V, 3-ph, 3-wire, 60Hz 
Optional: 50Hz Voltages
Merlin 350 through Merlin 400: 
190-205V, 3-ph, 3-wire, 50Hz 
208V-240V, 3-ph, 3-wire, 60Hz 
380-416V, 3-ph, 3-wire, 50Hz 
416-480V, 3-ph, 3-wire, 60Hz
208/416V,
3-phase
190/380V,
3-phase
240V,
1-phase HP Voltage CFM KW @ 240/480V, 3-phase
External Power
Merlin 100, Merlin 150: 
115V, 1-ph, 60Hz, 15A
Merlin 200 through 300: 
115V, 1-ph, 60Hz, 20A
Merlin 350, Merlin 400: 
230/460V, 3-ph, 50/60Hz, 20A
Voltage
High/Low Mode, operator selectable 
High: 250-480VAC, 3-ph. 
Low: to 240VAC, 3-ph. 
Optional: 1-ph.
Frequency
60Hz; Optional: 50, 400Hz
Duty Cycle
Continuous
Temperature Rating
125° F max intake air temp
Nominal 110° F rise
Power Connection
Merlin 100 through Merlin 300: 
4-wire plus ground
Merlin 350, Merlin 400: 
3-wire plus ground
© 2012 Simplex, Inc. All Rights Reserved.
Printed in the USA • 1103-03.01
Design subject to change without notice.
217-483-1600
Fax 217-483-1616
www.simplexdirect.com
Simplex, Inc.
5300 Rising Moon Road
Springfi eld, IL 62711-6228

MERLIN
100KW - 400KW Load Bank • Page 4
®
Dimensions and Key Features
1
H
Model W D H
Merlin 100KW, 150KW 31” 47” 43”
Merlin 200KW, 250KW, 300KW 31” 56” 50”
Merlin 350KW, 400KW 31” 69” 50”
WD
53
9
6
EXHAUST
AIR
4
8
10
11
INTAKE
AIR
2
7
RIGHT VIEW REAR VIEW LEFT VIEW
1. 12' Cable Set
2. Forklift Channels
3. Lockable Latch
4. Screened Intake and Exhaust
5. Hinged Access Door to Control 
Panel
6. Removeable Panel to Access 
Elements
7. Casters
8. External Control Power Cable
9. Hinged Access Door to Fuses and 
Contactors
10. Hand Grip for Moving and Cable 
Storage
11. Removeable Panel to Access Fan
Merlin 300 with optional Cam-Lok connectors
Simplex, Inc. 
5300 Rising Moon Road 
Springfi eld, IL 62711-6228
217-483-1600 
Fax 217-483-1616 
www.simplexdirect.com
© 2012 Simplex, Inc. All Rights Reserved. 
Printed in the USA • 1103-03.01 
Design subject to change without notice.