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GR-SENS Adjustable Current Limiting Protection Switch & Automatic Fuse


The GR-SENS is a compact fast-response overcurrent protection device, suitable for use with DC electric motors and actuators of many different shapes and sizes. It is designed to measure the current drawn by a motor/actuator and if it exceeds a Threshold Current (adjustable between 0.5-5.5A or between 1-15A, two versions are available) for longer than a Sensitivity Time (also adjustable, between 5-800ms) then the output is quickly turned off and a red LED illuminates to indicate a trip. A user can reset the device if it has tripped simply by turning the input off and then on again, or by reversing the input polarity (usually done via a controller or a switch). 

There are only four wires to connect, two labelled 'INPUT', which should be connected to the output of your controller or switch, and two labelled 'OUTPUT' which you should connect to your DC motor or actuator. 

Please read on below for more product information. An instructional information sheet is also included with each device. 


£28.90 £34.68 inc VAT
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Group SKU: GR-SENS

The GR-SENS, exclusive to Gimson Robotics, provides a significant improvement over the basic circuit protection used in many automation circuits. It is capable of quickly disconnecting power to a connected motor or actuator in the event of an overload. By allowing a user to adjust both a Threshold Current and Sensitivity Time value the response to an overload can be fine-tuned to the application, offering a much faster and more predictable response than thermal devices such as fuses or circuit breakers. 

The switch automatically resets itself if the input current is turned off and on again OR if the input polarity reverses/inverts, so you'll no longer need to go hunting for the correct size fuse or to find a tiny reset switch after an overload. These characteristics allow the GR-SENS to be used as a current-based limit switch in installations where it is difficult to mount a conventional limit switch circuit, since if it trips in one direction it then allows the user to reverse back in the opposite direction, away from the overload. 

Input and output example connection diagram for the GR-SENS current limiting switch


Two indicator LEDs, one Green power indicator and one Red status indicator, provide handy visual feedback of your circuit state. The power LED shows you when the device is receiving power from your controller or input supply while the status indicator will illuminate when the device has tripped and remain on until the device is reset. If a limit threshold (30A for >100ms) is breached the status LED will blink continuously (until the switch is reset) to warn you of the high current event.

It is an entirely solid-state switching device, using fets rather than mechanical relays to ensure reliable long-term operation.

Two versions of the device are available, selectable above. The 0.5-5.5A version is appropriate for operating smaller loads, enabling finer adjustments to the current setting at lower current values. This is best for actuator models like the GLA1500-N and GLA750. The 1A-15A version is suitable for larger motors and actuators, such as the GLA4000-S model.


The response of the controller is illustrated by the graphs below. Put simply, if the detected current exceeds the Threshold Current setting for LESS than the Sensitivity Time (as shown in the first graph, where t1 is less than the sensitivity time setting) then the device will not trip and current will continue to flow, however if the current exceeds the threshold for MORE than the Sensitivity Time then the output will be turned off and the current will go to zero (shown in the second graph, where t2 equals the time setting and the controller turning the output off is shown by the vertical fall in current).

5.5A Current Adjustment Example, 36% Turn
15A Current Adjustment Example, 100% Turn


Small screw-dials (adjusted with a small flat head or phillips screwdriver) allow you to tune the settings of each device. The available adjustments for Threshold Current are shown below for the two controller versions, the dials offer linear adjustment between two values. 

5.5A Current Adjustment Example, 36% Turn
15A Current Adjustment Example, 100% Turn


The adjustment for Sensitivity Time (in milliseconds) is shown below, which is the same for both the 5.5A and 15A version. 

Time Sensitivity Adjustment, 50% 400ms Adjustment Example

Instruction sheets are included with each device with different versions for the 5.5A and 15A options. Click on the links below to download a copy. 

GR-SENS Information Sheet, 5.5A Version (PDF, 1.8MB)

GR-SENS Information Sheet, 15A Version (PDF, 1.8MB)

A copy of the relevant instructions is included with each limit controller. 


Device Specifications


5.5A Version15A Version
Operating voltage:
5-30V DC
(the device may still operate at lower voltages if driven from a PWM controller)
Current threshold adjustment:
0.5 to 5.5 Amps
1 to 15 Amps
Time sensitivity adjustment:
5 to 800 milliseconds
Maximum limit threshold:
(Red LED should flash if this has been exceeded)
10A for >100ms30A for >100ms
Operating temperature:-5°C ~ +40°C
Ensure that there is free air flow around the device to prevent overheating
Maximum polarity inversion frequency:0.2Hz
Do not use this device for applications where the input polarity inverts more regularly than once every 5 seconds
Duty cycle rating:100%Average current <8A: 100%
Average current >8A: 40%, maximum 2 minutes continuous (limited by cooling)
Size & Weight:Main body size (inc heat shrink): 56 x 32mm
Weight: 62g, including leads and terminals
Input leads:300mm long 16AWG high temperature silicone, including micro automotive (type APS or ATT) blade fuse holder in-line with one lead
Output leads:300mm long 16AWG high temperature silicone
Failsafe fuse on input:
(Included as protection against hardware failure/damage only)
10A 'micro' blade fuse
30A 'micro' blade fuse
Input/Output connectors:6A-rated screw terminals
16A-rated screw terminals
Operating environment:0°C ~ +40°C
Ensure that the device is protected against water or extreme humidity


Please contact us if you have any technical or commercial questions about this item.

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