DMS Accessories
www.murata-ps.com
5 Amp AC Current Transformers
These commercial grade, UL & CSA recognized, “donut style” AC current-transformers
(CTs) provide an isolated 0-5A output that can be used with Murata Power Solutions’ ACA5
Series of digital ammeters. Installation is straightforward: simply pass the load-carrying
conductor through the 5A CT’s primary window, and then route its secondary’s leads
through the ACA5-ammeter’s built-in, low-burden, toroid sensor.
All models feature rugged, fully insulated construction, allowing continuous operation
with primary voltages up to 600Vac, at line frequencies from 50 to 400Hz. Fourteen models
are available to enable accurate measurements from 50A through 2000A. When combined
with Murata Power Solutions’ ACA5 Series ammeters, secondary lead-extensions may be
used for those applications where the CT cannot be installed in the immediate vicinity of
the ammeter.
GENERAL SPECIFICATIONS (ALL MODELS)
Insulation Class
Frequency Range
Supplied Secondary
Max. Secondary Lead
Rated Accuracy
Burden
600V, 10kV BIL full wave➀
50-400Hz
See Table 1
UL FIle No.
CSA File No.
TECHNICAL NOTES
Weight
IMPORTANT! To ensure safe and reliable operation, Current Transformers and asso-
ciated equipment must be installed and serviced by qualified technical personnel.
Never open the CT’s secondary connections while the primary is energized. Open
CT secondary wiring can generate potentially lethal voltages when the primary cir-
cuit is energized. Contact Murata Power Solutions if you have any doubts regarding
the installation or operation of any of our ac-mains measurement instruments and
accessories.
➀ Basic Lightning Impulse Insulation Level (BIL): The insulation
strength referenced to the crest value of an impulse voltage-
waveform which rises to a crest value in 1.2 microseconds, then
drops to ½ the crest value in 50 microseconds.
1. CT Precautions: In normal operation, a 5A current transformer’s secondary circuit oper-
ates at a relatively low voltage due to its closed-loop, low burden configuration (essentially
zero Ohms when used with Murata Power Solutions’ ACA5 series ammeters). However,
any CT can generate potentially lethal voltages if its output current is suddenly interrupted.
For example, loose secondary connections can produce a condition referred to as “induc-
tive kick.” Inductive kick can generate extremely high voltages across the open secondary
connections.
AC POWER
SUPPLY
ACA5-20PC-X-ACX
A
B
TB1
Therefore, all connections made to a CT’s secondary leads must only be performed with
zero current flowing in the primary circuit. Never operate a CT with its secondary circuit
open and current flowing in the primary.
TO AC LOAD
L1
5A CURRENT
TRANSFORMER
2. CT Connections and Grounding: Some applications require connecting one of the CT’s
5A output terminals to earth/chassis ground. In the USA, consult the latest revision of the
National Electrical Code for more information.
(see technical notes)
0-5A
OUTPUT
After all mechanical assembly is completed, pass the 5A secondary leads through the
ACA5 ammeter’s built-in toroid, then connect the two leads together as shown in Figure
1. For this connection, and for connections involving lead extensions, pressure-style
connectors (commonly called “wire nuts”) are acceptable as long as they are rated for the
currents and voltages involved.
Figure 1.Typical Connections
3. Installation: CT’s must be installed in a manner that ensures no excessive stresses are
applied to the primary conductor that passes through the CT or to the secondary circuit
and its associated instruments. Use plastic tie-wraps and/or other suitable non-conductive
restraining devices to secure the CT.
For full details go to
www.murata-ps.com/rohs
www.murata-ps.com/support
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