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DMS Accessories
5 Amp AC Current Transformers
MPM_DMS-CT.B05 Page 1 of 4
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.
TECHNICAL NOTES
(1) 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.
IMPORTANT! To ensure safe and reliable operation, Current Transformers and asso-
ciated equipment must be installed and serviced by qualied 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.
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 conguration (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.” I nductive kick can generate extremely high voltages across the open secondary
connections.
Therefore, all connections made to a CT ’s secondary leads must only be performed with
zero current owing in the primary circuit. Never operate a CT with its secondary circuit
open and current owing in the primary.
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.
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.
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.
Figure 1. Typical Connections
TB1
AB
ACA5-20PC-X-ACX
L1
AC POWER
SUPPLY
5A CURRENT
TRANSFORMER
TO AC LOAD
0-5A
OUTPUT
(see technical notes)
GENERAL SPECIFICATIONS (ALL MODELS)
Insulation Class 600V, 10kV BIL full wave (1)
Frequency Range 50-400Hz
Supplied Secondary
See Table 1
Max. Secondary Lead
Rated Accuracy
Burden
UL FIle No.
CSA File No.
Weight
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DMS Accessories
5 Amp AC Current Transformers
MPM_DMS-CT.B05 Page 2 of 4
TECHNICAL NOTES
Table 1. Selection Guide
burden column. Accuracy measurements are taken at 100% primary
current, using a resistive burden and a nominal line frequency of 60Hz.
7. Polarity: CTs are marked with ‘H1’ (primary) and ‘X1’ (secondary)
polarity indicators. When a CT ’s only function is to measure amperes,
polarity markings can be disregarded. However, correct polarity is
mandatory in applications in which the phase relationship between
two currents is involved (watt or watt-hour meters are two examples
of polarity sensitive applications). Refer to the respective instruments’
documentation for more information.
8. Thermal Rating Factor: The thermal rating factor denotes the amount
by which the primary current can be increased on a continuous
basis over its rated value without exceeding the CT’s maximum
temperature rise.
The formula below can be used to calculate thermal rating factors at
temperatures above 30°C.
4. Reference Documentation: Prior to connecting CTs to any measure-
ment device (analog or digital), relay, or other apparatus, be sure to
thoroughly review the applicable device’s technical documentation (for
example, Murata Power Solutions’ ACA5-20PC product data sheet). In
particular, make sure the CT’s ratings meet the requirements of your
application.
5. Secondary Lead Extensions: When calculating the total burden
imposed on a CT’s 5A output, Murata Power Solutions’ ACA5 digital
ammeters’ input impedance is negligible and can be assumed to be
zero Ohms. In many applications, the length of secondary wiring can
be increased up to the value specied in Table 1 without adversely
aecting performance.
In order to achieve the specied accuracy, the maximum permissible
burden must not exceed the value shown in Table 1. When used with
ACA5 ammeters, the total burden is the sum of the resistance of the
CT’s 24” leads and any lead-extensions. Make sure all connections
are securely tightened and properly strain relieved. If terminal blocks
are used for intermediary connections, refer to the manufacturer’s
torque recommendations.
Table 1 lists general guidelines for adding lead extensions when
using Murata Power Solutions’ ACA5-Series ammeters as the readout
device. The lengths in Table 1 assume the lead extensions are
16AWG. Stated dimensions are one-way distances between the ACA5
and the CT. Make sure all secondary extensions meet or exceed the
specications of the CT ’s built-in leads. In order to minimize external
noise pick up, lead extensions should be as kept short as possible.
6. Accuracy: The indicated accuracy specications are valid as long
as the total secondary burden does not exceed the value in Table 1’s
(85 - NAT)(RF)
2
NAT
NRF =
(85 - 55)(1.3)
2
55
NRF = = 0.96
NRF = Rating Factor at New Ambient Temperature
RF = 30°C Rating Factor
NAT = New Ambient Temperature
Example: Find the 55°C. thermal rating factor of a 2000:5 CT whose
30°C rating factor is 1.3.
MPS Part No. Current
Ratio
Accuracy (@
60Hz)
Burden VA
(Ohms)
Lead Ext.
Feet
(Meters)
Thermal Rating
Factor (@ 30ºC)
UL File
Cert #
CSA File
Cert # Leads Type Weight
(lb)
7020-01036-0 50:5 ±2% 1.5 (0.06) 4 (1.2) 1.3
E175133 Pending 16AWG, 24”
UL Style 3173 1.5
7020-01037-0 75:5 ±2% 3.0 (0.12) 10 (3.0) 1.3
7020-01038-0 100:5 ±1% 3.0 (0.12) 10 (3.0) 1.3
7020-01039-0 150:5 ±1% 6.0 (0.24) 20 (6.1) 1.3
7020-01040-0 200:5 ±1% 8.0 (0.32) 30 (9.1) 1.3
7020-01041-0 250:5 ±1% 10.0 (0.40) 40 (12.2) 1.3
7020-01123-0 300:5 ±1% 12.5 (0.50) 50 (15.2) 1.0
E466945 260320
16AWG, 24”
UL Style 1015
1.0
7020-01124-0 400:5 ±1% 12.5 (0.50) 50 (15.2) 1.0
7020-01125-0 500:5 ±1% 20.0 (0.80) 80 (24.4) 1.0
7020-01042-0 600:5 ±1% 10.0 (0.40) 40 (12.2) 1.0
E228202 223647 1.5
7020-01043-0 750:5 ±1% 10.0 (0.40) 40 (12.2) 1.0
7020-01044-0 1000:5 ±1% 10.0 (0.40) 40 (12.2) 1.0
7020-01045-0 1500:5 ±1% 12.5 (0.50) 50 (15.2) 1.0
7020-01046-0 2000:5 ±1% 15.0 (0.60) 60 (18.3) 1.0
See www.murata-ps.com/dpm-availability for model-specific availability.
www.murata-ps.com/support
DMS Accessories
5 Amp AC Current Transformers
MPM_DMS-CT.B05 Page 3 of 4
MECHANICAL SPECIFICATIONS
Models: 7020-01036-0 – (50:5)
7020-01037-0 – (75:5)
7020-01038-0 – (100:5)
7020-01039-0 – (150:5)
7020-01040-0 – (200:5)
7020-01041-0 – (250:5)
Models: 7020-01123-0 – (300:5)
7020-01124-0 – (400:5)
7020-01125-0 – (500:5)
Models: 7020-01042-0 – (600:5)
7020-01043-0 – (750:5)
7020-01044-0 – (1000:5)
7020-01045-0 – (1500:5)
7020-01046-0 – (2000:5)
X1
H1
H1
X1
1.56
(39.6)
DIA
1.10 (27.9)
3.56
(90.4)
X1
H1
H1
X1
1.2
(30.5)
DIA
1.4 (35.6)
2.7
(68.6)
X1
H1
H1
X1
3.00
(76.2)
DIA
1.13 (28.7)
4.50
(114.3)
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Murata Power Solutions, Inc. makes no representation that the use of its products in the circuits described herein, or the use of other
technical information contained herein, will not infringe upon existing or future patent rights. The descriptions contained herein do not imply
the granting of licenses to make, use, or sell equipment constructed in accordance therewith. Specifications are subject to change without
notice. © 2018 Murata Power Solutions, Inc.
Murata Power Solutions, Inc.
ISO 9001 and 14001 REGISTERED
This product is subject to the following operating requirements
and the Life and Safety Critical Application Sales Policy:
Refer to: http://www.murata-ps.com/requirements/
DMS Accessories
5 Amp AC Current Transformers
MPM_DMS-CT.B05 Page 4 of 4
NOTES
