SIEMENS
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Siemens IC 10 · 2017
Relays
SIRIUS 3UG48 Monitoring Relays for Stand-Alone Installation for IO-Link
Power factor and active current monitoring
10
■
Overview
SIRIUS 3UG4841 monitoring relay
The 3UG4841 power factor and active current monitoring
devices enable the load monitoring of motors.
Whereas power factor (p.f.) monitoring is used above all for
monitoring no-load operation, the active current monitoring
option can be used to observe and evaluate the load factor over
the entire torque range.
■
Benefits
•
Monitoring of even small single-phase motors with a no-load
supply current below 0.5 A
•
Simple determination of threshold values by the direct
collection of measured variables on motor loading
•
Range monitoring and active current measurement enable de-
tection of cable breaks between control cabinets and motors,
as well as phase failures
•
Power factor (p.f.) and/or
I
res
(active current) can be selected
as the measurement principle
•
Width 22.5 mm
•
Display and transmission of actual value and status messages
to controller
•
All versions with removable terminals
•
All versions with screw or spring-type terminals
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Application
•
No-load monitoring and load shedding, such as in the event
of a V-belt tear
•
Underload monitoring in the low-end performance range,
e.g. in the event of pump no-load operation
•
Monitoring of overload, e.g. due to a dirty
filter system
•
Power factor monitoring in networks for control of
compensation equipment
•
Broken cable between control cabinet and motor
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Technical specifications
3UG4841 monitoring relays
The 3UG4841 monitoring relays are supplied with power through
IO-Link or with an external auxiliary voltage of 24 V DC and are
used for performing overshoot, undershoot or range monitoring
of the power factor and/or the resulting active current, depend-
ing on parameterization. The load to be monitored is connected
upstream of the IN terminal. The load current flows through the
terminals IN and Ly/N. The setting range for the power factor is
0 to 0.99 and for the active current
I
res
it is 0.2 to 10 A. If the con-
trol supply voltage is switched on and no load current flows, the
display will show
I
< 0.2 and a symbol for overrange, under-
range or range monitoring. If the motor is now switched on and
the current exceeds 0.2 A, the set ON-delay time onDel begins.
During this time, if the set limit values are undershot or ex-
ceeded, this does not lead to a relay reaction of the changeover
contact. If the operational flowing active current and/or the p.f.
value falls below or exceeds the respective set threshold value,
the tripping delay time begins. When this time has expired, the
relay changes its switch position. The relevant measured vari-
ables for overshooting and undershooting in the display flash. If
monitoring for active current undershoot is switched off
(
I
res
▼
= OFF), and if the load current undershoots the lower
measuring range threshold (0.2 A), the CO contacts remain
unchanged. If a threshold value is set for the monitoring of active
current undershooting, then undershooting of the measuring
range threshold (0.2 A) will result in a response of the
CO contacts.
The relay operates either according to the open-circuit or
closed-circuit principle.
If the device is set to Auto RESET (Memory = No), depending
on the set principle of operation, the switching relay returns to its
initial state and the flashing ends when the hysteresis threshold
is reached.
If Manual RESET is selected in the menu (Memory = Yes), the
switching relay remains in its current switching state and the
current measured value and the symbol for undershooting and
overshooting continues to flash, even when the measured vari-
able reaches a permissible value again. This stored fault status
can be reset by simultaneously pressing the UP
▲
and DOWN
▼
keys for 2.5 s.
With Manual RESET through IO-Link it is possible in addition to
set whether error signals are to be deleted when the control sup-
ply voltage is switched off and on (as remote RESET) or whether
the signals are to be permanently saved even in a voltage failure,
with confirmation possible only through local RESET or via
IO-Link.
© Siemens AG 2016