On the same graph with the 3 data plots that we gathered last week, I put in the ideal profile temperature using the estimation method.
I also made some studies about the solid state relay to better understand how it works and functions.
A solid state relay is an ON-OFF control device in which the load current is conducted by one or more semiconductors, like a power transistor or thyristor.
Like all relays, the SSR requires relatively low-control circuit energy to switch the output state from OFF to ON, and vice versa. Since this control energy is very much lower than the output power controllable by the relay at full load, “power gain” in an SSR is substantial–frequently much higher than in an electromagnetic relay of comparable output rating. To put it another way, the sensitivity of an SSR is often significantly higher than that of an EMR of comparable output rating.
There are 3 major categories of SSR:
- Reed-Relay-Coupled SSR: in which the control signal is applied (directly, or through a preamplifier) to the coil of a reed relay. The closure of the reed switch then activates appropriate circuitry that triggers the thyristor switch. Clearly, the input-output isolation achieved is that of the reed relay, which is usually excellent.
- Transformer-Coupled SSR: in which the control signal is applied (through a DC-AC converter, if it is DC, or directly, if It is AC) to the primary of a small, low-power transformer, and the secondary voltage that results from the primary excitation is used (with or without rectification, amplification, or other modification) to trigger the thyristor switch. In this type, the degree of input-output isolation depends on the design of the transformer.
- Photo-Coupled SSR: in which the control signal is applied to a light or infrared source (usually, a light-emitting diode, or LED), and the radiation from that source is detected in a photo-sensitive semi-conductor (i.e., a photosensitive diode, a photo-sensitive transistor, or a photo-sensitive thyristor). The output of the photo-sensitive device is then used to trigger (gate) the TRIAC or the SCR’s that switch the load current. Clearly, the only significant “coupling path” between input and output is the beam of light or infra- red radiation, and electrical isolation is excellent. These SSR’s are also referred to as “optically coupled” or “photo-isolated”.
Resource: http://www.omega.com/temperature/Z/pdf/z124-127.pdf
The SSR that we’ll use is the SSR-25DA 25Amp 380v, which is easily driven from the Arduino’s redboard output pin.
– Input
– Operating Voltage:3~32VDC
– Min. ON/OFF Voltage:ON>2.4V , OFF<1.0V
– Trigger Current:7.5mA / 12V
– Control Method:Zero Cross Trigger
– Output
– Operating Voltage:24~380VAC
– Min. Back Voltage:600 VAC (Repetive)
– Voltage Drop:1.6V / 25°C
– Max. Pulse Current:275A
– Leakage Current:3.0mA
– Response Time:ON<10ms , OFF<10ms
– General Data
– Dielectric Strength:Over 2.5KVAC / 1min.
– Isolation Strength:Over 50MO / 500VDC
– Operating Temperature:-20°C ~ +80°C
– Housing Material:Intensive ABS
– Weight:139g
Link: http://yourduino.com/sunshop2/index.php?l=product_detail&p=216
