CM-SRN

What does this relay do?

This unit is an electronic current monitoring relay designed to supervise a measured current and change its output state when the value moves above or below a set threshold. It is commonly used where a machine, circuit or load needs to be monitored for normal current draw, overload or loss of load.

Can it monitor both overcurrent and undercurrent conditions?

Yes. The relay can be configured for either overcurrent or undercurrent monitoring using the front controls. That makes it suitable for applications where you want to detect a current rising too high or dropping below an expected operating level.

Which current ranges can be selected?

The CM-SRN provides selectable measuring ranges via its input terminals. Typical ranges are 0.3-1.5 A, 1-5 A and 3-15 A, allowing the user to match the relay more closely to the application and improve switching accuracy.

Is the switching threshold adjustable?

Yes. The threshold is adjustable on the front of the relay, so the trip point can be set within the selected measuring range. This helps when adapting the device to different load conditions without changing the relay itself.

Does it have adjustable hysteresis?

Yes. The switching hysteresis is adjustable, typically from 5% to 30% of the set value. This is useful for reducing contact chatter and preventing nuisance switching when the measured current fluctuates around the threshold.

Can a time delay be set before the relay changes state?

Yes. The device includes an adjustable delay function, with selectable ranges of 0.05-1 s and 1.5-30 s. This allows short transients or brief inrush conditions to pass without causing an unnecessary output change.

What output contacts does it provide?

This model provides 2 changeover relay outputs. In typical ratings, the contacts are suitable for up to 5 A in AC-12 at 230 V, 3 A in AC-15 at 230 V, 5 A in DC-12 at 24 V and 2.5 A in DC-13 at 24 V.

How is the operating status shown?

The front panel uses LED indication for quick status checking. A green LED shows the presence of the supply voltage, and a yellow LED indicates the relay output state.

How is the relay mounted in a panel?

The relay is designed for DIN rail mounting. It has a 45 mm housing width, which makes it suitable for control panels where a larger-format monitoring relay with front adjustment and dual output contacts is preferred.

What kinds of applications is it suited to?

It is well suited to monitoring motor current, heater circuits, lighting circuits and other electrical loads where the current level is a useful indication of operating condition. Typical uses include detecting overload, identifying loss of load, confirming equipment is running and monitoring abnormal current draw.

Can it be used with an external current transformer?

In applications where the line current needs to be scaled to a suitable monitoring value, an external current transformer can be used so that the relay measures the proportional secondary current instead of the full primary current directly. This can be useful in higher-current installations.

What are the typical environmental and installation characteristics?

The relay is intended for control cabinet installation and is typically rated for operation from -25 °C to +65 °C, with storage down to -40 °C and up to +85 °C. It is housed to approximately IP50 at the enclosure and IP20 at the terminals, which is typical for DIN rail control components.