CH Series PID Temperature Controller: Sizes, Input and Output Codes, Alarm Modes

The CH series is a short-body PID temperature controller used where cabinet depth is tight — injection moulding machines, packaging equipment, heat sealers and industrial ovens. The body is only 70mm deep, which is the main practical difference from the longer REX-C series. Ordering data is on the CH series product page.

1. Sizes and cutouts

Parameter	Specification
CH102	48 × 48mm panel, 44×44mm cutout
CH402	48 × 96mm panel, 44×92mm cutout
CH702	72 × 72mm panel, 68×68mm cutout
CH902	96 × 96mm panel, 92×92mm cutout
Body depth	70mm on all sizes

Cutout tolerance is +1/0mm. Other sizes should be confirmed before ordering.

2. Electrical specification

Parameter	Specification
Display	Dual LED for PV and SV
Control method	PID with auto-tuning; reverse-acting (F) for heating or direct-acting (D) for cooling
Input	Thermocouple, Pt100, Cu50, 0–5V, 1–5V and mA signals, selected by input letter plus range code (for example K02)
Control output	N none; M relay contact; V SSR drive voltage pulse; 8 current output; T SCR zero-crossing; G SCR phase-angle pulse
Alarm output	ALM1 and ALM2, selectable A–L deviation, band, absolute and standby modes
Supply	85–265VAC, 50Hz
Accuracy	±0.5% FS
Sampling period	0.5s
Operating environment	0 to 50°C, 30–85% RH

3. Choosing the output code

• M (relay) — drives a contactor coil. Simplest and cheapest; keep the cycle time long to protect the contacts.
• V (SSR drive) — a voltage pulse for a DC-input solid state relay such as the SSR-DA series. Use this for fast zones and tighter control.
• 8 (current output) — 4–20mA into a modulating valve or an SCR power regulator.
• T / G (SCR trigger) — zero-crossing or phase-angle pulse for a pulse-triggered SCR module. Phase angle gives stepless power; zero-crossing gives lower electrical noise.

4. Alarm modes

CH alarms are relative to the setpoint unless an absolute mode is selected, which is the most common source of confusion on site.

• Deviation alarm — trips at setpoint plus or minus the alarm value, so it moves with the setpoint.
• Absolute alarm — trips at a fixed temperature regardless of setpoint. Use this for over-temperature protection.
• Band alarm — trips whenever PV leaves a window around setpoint; useful for detecting a failed heater.
• Standby variants — suppress the alarm during initial heat-up so start-up does not raise a nuisance trip.

5. Commissioning

• Confirm the input code matches the fitted sensor, and that the range code covers the working temperature.
• Select F (reverse acting) for heating; D (direct acting) is for cooling and will appear as a controller that never fires.
• Set an absolute high alarm below the machine safe limit and prove it by lowering the alarm setpoint temporarily.
• Run auto-tune at the working setpoint with the real load; retune after any change in load mass or heater rating.
• Verify PV stability over at least one full process cycle before releasing the machine.

6. FAQ

What is the difference between CH and REX-C?

Same control platform and parameter logic; CH uses a 70mm short body for shallow cabinets, while REX-C uses the longer standard body. Comparison data is on the REX series page.

Can I replace a failed CH102 with a CH702?

Only if the panel cutout is changed — CH102 needs 44×44mm, CH702 needs 68×68mm. Electrically the wiring and parameters are equivalent.

My alarm trips during every start-up. What should I change?

Select a standby alarm variant so the alarm arms only after PV first reaches setpoint.

Which output should I order for a hot runner?

V (SSR drive) with a correctly heat-sunk solid state relay, because hot runner zones cycle far too fast for a mechanical contactor.

Questions on model codes: sales@strong-ele.com.