ACI-Automation Components A/MCS-A, A/MSCS-A Instruction Sheet

Installation and Operation Instructions

#8 x 3/4" Tek Screw

(Qty. 2/Unit)

!

Part #A/MCS-A, A/MSCS-A

Please Read Instructions Carefully Before Installation!

 Safety

 This product is not intended to be used for Life or Safety applications.
 This product is not intended for use in any hazardous or classified locations.
 Disconnect and lock out all power sources before installation as severe injury or death may result from electrical

shock due to contact with high voltage wires. 



 Installation

Make sure that all installations are in compliance with all national and local electrical codes. Only qualified individuals that are
familiar with codes, standards, and proper safety procedures for high-voltage installations should attempt installation. The current
switches will not require external power, since the power for the current switch is induced from the conductor being monitored.

Warning: Never rely on the LED’s to determine whether power is present at the current switch. The Red LED will

indicate whether the current is above the adjustable trip point. The Blue LED will indicate that the

The A/MCS-A and A/MSCS-A Current Switches should be used on Insulated Conductors Only! The current switch may be

mounted in any position using the (2) #8 x 3/4” Tek screws and the mounting holes in the base. Leave a minimum distance of
1” (3 cm) between the current switch and any other magnetic devices such as contactors and transformers.

current is below the adjustable trip point.

Figure 1: A/MCS-A Figure 2: A/MSCS-A

For applications in which the normal operating current is below the 0.32Amps (A/MCS-A) or 0.70Amps (A/MSCS-A)
trip point (See Figure 3 below), the conductor being monitored may be looped through the sensor 6 times giving you a total
operating current of 6X the original current. Example: A small fan operating at 0.2A should be wrapped through the sensor
7 times to give you a total operating current of 1.4Amps flowing through the A/MCS-A or A/MSCS-A.

Figure 3: Wires Through Sensors

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For applications in which the normal operating current is greater than 150 Amps or for conductor diameters larger than 0.530”

Insulated

Example: For currents up to 600 Amps
(and not below 70 Amps (A/MCS-A)
or 95 Amps (A/MSCS-A), where
Current Transformer (C.T.)
secondary falls below 1 Amp
use a 600:5 ratio C.T. as shown:

Nut

Conductor

600:5 Ratio 5A C.T.

Wire

System

Building Management

Digital Input #1

24 VAC

Line

120 VAC

24 VAC Coil

(Status)

Contactor)

Transformer

(Relay Coil or

DO

Relay / Contactor

DDC Controller

DI

ACI Model #

Adjustable Trip

Point

Output Switch Rating

Max. Sensing

Current Voltage

Max. Continuous

Current

Max. Current for

6 seconds

Max. Current for

1 second

A/MCS-A

0.32 - 150 Amps

1.00 Amp @ 36 VAC/VDC

600 VAC

158 Amps

240 Amps

600 Amps

A/MSCS-A

0.70 - 150 Amps

1.00 Amp @ 36 VAC/VDC

600 VAC

158 Amps

240 Amps

600 Amps

(1.35 cm) in diameter, an external 5 Amp Current Transformer must be used as shown in Figure 4 below. Remember that the
secondary of the 5A CT must be shorted together before the power may be turned onto the monitored device.

Figure 4: Current Transformer

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 Wiring

ACI recommends the use of a two conductor 16 to 22 AWG shielded cable or twisted pair copper wire only for all current switch

applications. A maximum wire length of less than 30 meters (98.4 feet) should be used between the A/MCS-A and A/MSCS-A
current switches and the Building Management System or controller. Note: When using a shielded cable, be sure to connect
only (1) end of the shield to ground at the controller. Connecting both ends of the shield to ground may cause a ground loop.
When removing the shield from the sensor end, make sure to properly trim the shield so as to prevent any chance of sh orting. The
current switch output terminals represent a solid-state switch for controlling both AC and DC loads and is not polarity sensitive.
The recommended torque to be used on the terminal block connections is 0.67 Nm or 5.93 in-lbs... The aperture (hole) size of the
current switch is 0.53” (1.35 cm) and will accept a 1 AWG maximum wire diameter.



 Operating Specifications

See Figure 5 and Figure 6 for two different current switch applications using your Building Management System (DDC/PLC
Controller). Figure 5 is showing the use of the Adjustable Current Switch as a Digital Input to your DDC Controller, whereas
Figure 6 is showing you how to use the Adjustable Current Switch in conjunction with your building management system to
monitor belt loss on a motor.

Figure 5: Digital Circuit Figure 6: Analog Circuit

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