Protection Relays
Alternating Relays
50R-400-ALT
480VAC application, panel mount
Description
The 50R-400-ALT alternating relays are used to alternate
between two loads, most commonly in duplex pumping and
compressor applications to balance the runtime of both loads.
When used in single float applications, the alternating relay
changes state after the float switch opens*, forcing the other
pump to run the next time the float closes. When used in dual
float applications, the alternating relay will allow both pumps to
run simultaneously when the lead and lag floats are both closed.
An adjustment knob provides the option to force one pump to
run every time the float switch is closed. This is helpful when
one pump has been removed for repair or for test purposes.
A built-in debounce feature prevents the alternating relay from
changing state if the float contact bounces momentarily.
*The alternating relay will not switch states while current is flowing. Switching will only occur
after current has been sensed, followed by loss of current for the duration of the debounce
time delay.
Wiring Diagram
Features & Benefits
FEATURES
Debounce time delay
LED indicators
Built-in manual switch
to force load operation
Operates from
380 - 480VAC
BENEFITS
Prevents rapid cycling caused by waves or splashing
in the tank
Visual indication of load operation in
duplex application
Helpful to control load operation when performing
periodic maintenance or pump repair
No transformer required to provide 120 - 240V for
control circuit
Specifications
Input Characteristics
Supply Voltage
Supply Current
Functional Characteristics
Control Input Impedance (min)
Output Characteristics
Output Contact Rating
Pilot Duty
General Purpose
Debounce Time Delay
General Characteristics
Maximum Input Power
Terminal
Torque
Wire Size
Safety Marks
UL
CE
Dimensions
Weight
Mounting Method
380-480VAC
40mA
1MΩ
470VA @ 600VAC
10A
1 second
5W
7 in.-lbs.
12-18AWG
UL508 (File #E68520)
IEC 60947
H
74.4 mm (2.93”);
W
133.9 mm (5.27”);
D
74.9 mm (2.95”)
0.98 lb. (15.68 oz., 444.52 g)
#8 screws
© 2017 Littelfuse Protection Relays & Controls
www.littelfuse.com/50r400alt
Rev: 1-B-100417
RF/Wirelessly
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