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

Installation and Operation Instructions

#8 x 3/4" Tek Screw

(Qty. 2/Unit)

!

Part #A/MCS, A/MSCS

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.

The A/MCS and A/MSCS 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.

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

For applications in which the normal operating current is below the 0.20 Amps (A/MCS) or 0.55 Amps (A/MSCS)
trip point (See Figure 3 below), the conductor being monitored may be looped through the sensor 4 times giving you a total
operating current of 4X the original current. Example: A small fan operating at 0.2A should be wrapped through the sensor
4 times to give you a total operating current of 0.8Amps flowing through the A/MCS or A/MSCS.

Figure 3: Wires Through Sensors

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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

Building Management

Digital Input #1

System

(Relay Coil or

120 VAC

Line

Transformer

24 VAC

Contactor)

24 VAC Coil

Relay / Contactor

DI

DO

(Status)

DDC Controller

ACI Model #

Fixed Trip Point

Output Switch Rating

Max. Sensing

Current Voltage

Max. Continuous

Current

Max. Current for

6 seconds

Max. Current for

1 second

A/MCS

0.20 Amps

0.50 Amp @ 36 VAC/VDC

600 VAC

158 Amps

240 Amps

600 Amps

A/MSCS

0.55 Amps

0.50 Amp @ 36 VAC/VDC

600 VAC

158 Amps

240 Amps

600 Amps

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



 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 and A/MSCS 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 shorting. 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 Go/No Go Current Switch as a Digital Input to your DDC Controller, whereas
Figure 6 is showing you how to use the Go/No/Go Current Switch in conjunction with your building management system to
control a fan or pump for example.

Figure 5: Digital Circuit Figure 6: Analog Circuit

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